text: # Author: Steven J. Bethard <steven.bethard@gmail.com>.
  
  """Command-line parsing library
  
  This module is an optparse-inspired command-line parsing library that:
  
      - handles both optional and positional arguments
      - produces highly informative usage messages
      - supports parsers that dispatch to sub-parsers
  
  The following is a simple usage example that sums integers from the
  command-line and writes the result to a file::
  
      parser = argparse.ArgumentParser(
          description='sum the integers at the command line')
      parser.add_argument(
          'integers', metavar='int', nargs='+', type=int,
          help='an integer to be summed')
      parser.add_argument(
          '--log', default=sys.stdout, type=argparse.FileType('w'),
          help='the file where the sum should be written')
      args = parser.parse_args()
      args.log.write('%s' % sum(args.integers))
      args.log.close()
  
  The module contains the following public classes:
  
      - ArgumentParser -- The main entry point for command-line parsing. As the
          example above shows, the add_argument() method is used to populate
          the parser with actions for optional and positional arguments. Then
          the parse_args() method is invoked to convert the args at the
          command-line into an object with attributes.
  
      - ArgumentError -- The exception raised by ArgumentParser objects when
          there are errors with the parser's actions. Errors raised while
          parsing the command-line are caught by ArgumentParser and emitted
          as command-line messages.
  
      - FileType -- A factory for defining types of files to be created. As the
          example above shows, instances of FileType are typically passed as
          the type= argument of add_argument() calls.
  
      - Action -- The base class for parser actions. Typically actions are
          selected by passing strings like 'store_true' or 'append_const' to
          the action= argument of add_argument(). However, for greater
          customization of ArgumentParser actions, subclasses of Action may
          be defined and passed as the action= argument.
  
      - HelpFormatter, RawDescriptionHelpFormatter, RawTextHelpFormatter,
          ArgumentDefaultsHelpFormatter -- Formatter classes which
          may be passed as the formatter_class= argument to the
          ArgumentParser constructor. HelpFormatter is the default,
          RawDescriptionHelpFormatter and RawTextHelpFormatter tell the parser
          not to change the formatting for help text, and
          ArgumentDefaultsHelpFormatter adds information about argument defaults
          to the help.
  
  All other classes in this module are considered implementation details.
  (Also note that HelpFormatter and RawDescriptionHelpFormatter are only
  considered public as object names -- the API of the formatter objects is
  still considered an implementation detail.)
  """
  
  __version__ = '1.1'
  __all__ = [
      'ArgumentParser',
      'ArgumentError',
      'ArgumentTypeError',
      'FileType',
      'HelpFormatter',
      'ArgumentDefaultsHelpFormatter',
      'RawDescriptionHelpFormatter',
      'RawTextHelpFormatter',
      'MetavarTypeHelpFormatter',
      'Namespace',
      'Action',
      'ONE_OR_MORE',
      'OPTIONAL',
      'PARSER',
      'REMAINDER',
      'SUPPRESS',
      'ZERO_OR_MORE',
  ]
  
  
  import collections as _collections
  import copy as _copy
  import os as _os
  import re as _re
  import sys as _sys
  import textwrap as _textwrap
  
  from gettext import gettext as _, ngettext
  
  
  SUPPRESS = '==SUPPRESS=='
  
  OPTIONAL = '?'
  ZERO_OR_MORE = '*'
  ONE_OR_MORE = '+'
  PARSER = 'A...'
  REMAINDER = '...'
  _UNRECOGNIZED_ARGS_ATTR = '_unrecognized_args'
  
  # =============================
  # Utility functions and classes
  # =============================
  
  class _AttributeHolder(object):
      """Abstract base class that provides __repr__.
  
      The __repr__ method returns a string in the format::
          ClassName(attr=name, attr=name, ...)
      The attributes are determined either by a class-level attribute,
      '_kwarg_names', or by inspecting the instance __dict__.
      """
  
      def __repr__(self):
          type_name = type(self).__name__
          arg_strings = []
          star_args = {}
          for arg in self._get_args():
              arg_strings.append(repr(arg))
          for name, value in self._get_kwargs():
              if name.isidentifier():
                  arg_strings.append('%s=%r' % (name, value))
              else:
                  star_args[name] = value
          if star_args:
              arg_strings.append('**%s' % repr(star_args))
          return '%s(%s)' % (type_name, ', '.join(arg_strings))
  
      def _get_kwargs(self):
          return sorted(self.__dict__.items())
  
      def _get_args(self):
          return []
  
  
  def _ensure_value(namespace, name, value):
      if getattr(namespace, name, None) is None:
          setattr(namespace, name, value)
      return getattr(namespace, name)
  
  
  # ===============
  # Formatting Help
  # ===============
  
  class HelpFormatter(object):
      """Formatter for generating usage messages and argument help strings.
  
      Only the name of this class is considered a public API. All the methods
      provided by the class are considered an implementation detail.
      """
  
      def __init__(self,
                   prog,
                   indent_increment=2,
                   max_help_position=24,
                   width=None):
  
          # default setting for width
          if width is None:
              try:
                  width = int(_os.environ['COLUMNS'])
              except (KeyError, ValueError):
                  width = 80
              width -= 2
  
          self._prog = prog
          self._indent_increment = indent_increment
          self._max_help_position = max_help_position
          self._max_help_position = min(max_help_position,
                                        max(width - 20, indent_increment * 2))
          self._width = width
  
          self._current_indent = 0
          self._level = 0
          self._action_max_length = 0
  
          self._root_section = self._Section(self, None)
          self._current_section = self._root_section
  
          self._whitespace_matcher = _re.compile(r'\s+', _re.ASCII)
          self._long_break_matcher = _re.compile(r'\n\n\n+')
  
      # ===============================
      # Section and indentation methods
      # ===============================
      def _indent(self):
          self._current_indent += self._indent_increment
          self._level += 1
  
      def _dedent(self):
          self._current_indent -= self._indent_increment
          assert self._current_indent >= 0, 'Indent decreased below 0.'
          self._level -= 1
  
      class _Section(object):
  
          def __init__(self, formatter, parent, heading=None):
              self.formatter = formatter
              self.parent = parent
              self.heading = heading
              self.items = []
  
          def format_help(self):
              # format the indented section
              if self.parent is not None:
                  self.formatter._indent()
              join = self.formatter._join_parts
              item_help = join([func(*args) for func, args in self.items])
              if self.parent is not None:
                  self.formatter._dedent()
  
              # return nothing if the section was empty
              if not item_help:
                  return ''
  
              # add the heading if the section was non-empty
              if self.heading is not SUPPRESS and self.heading is not None:
                  current_indent = self.formatter._current_indent
                  heading = '%*s%s:\n' % (current_indent, '', self.heading)
              else:
                  heading = ''
  
              # join the section-initial newline, the heading and the help
              return join(['\n', heading, item_help, '\n'])
  
      def _add_item(self, func, args):
          self._current_section.items.append((func, args))
  
      # ========================
      # Message building methods
      # ========================
      def start_section(self, heading):
          self._indent()
          section = self._Section(self, self._current_section, heading)
          self._add_item(section.format_help, [])
          self._current_section = section
  
      def end_section(self):
          self._current_section = self._current_section.parent
          self._dedent()
  
      def add_text(self, text):
          if text is not SUPPRESS and text is not None:
              self._add_item(self._format_text, [text])
  
      def add_usage(self, usage, actions, groups, prefix=None):
          if usage is not SUPPRESS:
              args = usage, actions, groups, prefix
              self._add_item(self._format_usage, args)
  
      def add_argument(self, action):
          if action.help is not SUPPRESS:
  
              # find all invocations
              get_invocation = self._format_action_invocation
              invocations = [get_invocation(action)]
              for subaction in self._iter_indented_subactions(action):
                  invocations.append(get_invocation(subaction))
  
              # update the maximum item length
              invocation_length = max([len(s) for s in invocations])
              action_length = invocation_length + self._current_indent
              self._action_max_length = max(self._action_max_length,
                                            action_length)
  
              # add the item to the list
              self._add_item(self._format_action, [action])
  
      def add_arguments(self, actions):
          for action in actions:
              self.add_argument(action)
  
      # =======================
      # Help-formatting methods
      # =======================
      def format_help(self):
          help = self._root_section.format_help()
          if help:
              help = self._long_break_matcher.sub('\n\n', help)
              help = help.strip('\n') + '\n'
          return help
  
      def _join_parts(self, part_strings):
          return ''.join([part
                          for part in part_strings
                          if part and part is not SUPPRESS])
  
      def _format_usage(self, usage, actions, groups, prefix):
          if prefix is None:
              prefix = _('usage: ')
  
          # if usage is specified, use that
          if usage is not None:
              usage = usage % dict(prog=self._prog)
  
          # if no optionals or positionals are available, usage is just prog
          elif usage is None and not actions:
              usage = '%(prog)s' % dict(prog=self._prog)
  
          # if optionals and positionals are available, calculate usage
          elif usage is None:
              prog = '%(prog)s' % dict(prog=self._prog)
  
              # split optionals from positionals
              optionals = []
              positionals = []
              for action in actions:
                  if action.option_strings:
                      optionals.append(action)
                  else:
                      positionals.append(action)
  
              # build full usage string
              format = self._format_actions_usage
              action_usage = format(optionals + positionals, groups)
              usage = ' '.join([s for s in [prog, action_usage] if s])
  
              # wrap the usage parts if it's too long
              text_width = self._width - self._current_indent
              if len(prefix) + len(usage) > text_width:
  
                  # break usage into wrappable parts
                  part_regexp = r'\(.*?\)+|\[.*?\]+|\S+'
                  opt_usage = format(optionals, groups)
                  pos_usage = format(positionals, groups)
                  opt_parts = _re.findall(part_regexp, opt_usage)
                  pos_parts = _re.findall(part_regexp, pos_usage)
                  assert ' '.join(opt_parts) == opt_usage
                  assert ' '.join(pos_parts) == pos_usage
  
                  # helper for wrapping lines
                  def get_lines(parts, indent, prefix=None):
                      lines = []
                      line = []
                      if prefix is not None:
                          line_len = len(prefix) - 1
                      else:
                          line_len = len(indent) - 1
                      for part in parts:
                          if line_len + 1 + len(part) > text_width and line:
                              lines.append(indent + ' '.join(line))
                              line = []
                              line_len = len(indent) - 1
                          line.append(part)
                          line_len += len(part) + 1
                      if line:
                          lines.append(indent + ' '.join(line))
                      if prefix is not None:
                          lines[0] = lines[0][len(indent):]
                      return lines
  
                  # if prog is short, follow it with optionals or positionals
                  if len(prefix) + len(prog) <= 0.75 * text_width:
                      indent = ' ' * (len(prefix) + len(prog) + 1)
                      if opt_parts:
                          lines = get_lines([prog] + opt_parts, indent, prefix)
                          lines.extend(get_lines(pos_parts, indent))
                      elif pos_parts:
                          lines = get_lines([prog] + pos_parts, indent, prefix)
                      else:
                          lines = [prog]
  
                  # if prog is long, put it on its own line
                  else:
                      indent = ' ' * len(prefix)
                      parts = opt_parts + pos_parts
                      lines = get_lines(parts, indent)
                      if len(lines) > 1:
                          lines = []
                          lines.extend(get_lines(opt_parts, indent))
                          lines.extend(get_lines(pos_parts, indent))
                      lines = [prog] + lines
  
                  # join lines into usage
                  usage = '\n'.join(lines)
  
          # prefix with 'usage:'
          return '%s%s\n\n' % (prefix, usage)
  
      def _format_actions_usage(self, actions, groups):
          # find group indices and identify actions in groups
          group_actions = set()
          inserts = {}
          for group in groups:
              try:
                  start = actions.index(group._group_actions[0])
              except ValueError:
                  continue
              else:
                  end = start + len(group._group_actions)
                  if actions[start:end] == group._group_actions:
                      for action in group._group_actions:
                          group_actions.add(action)
                      if not group.required:
                          if start in inserts:
                              inserts[start] += ' ['
                          else:
                              inserts[start] = '['
                          inserts[end] = ']'
                      else:
                          if start in inserts:
                              inserts[start] += ' ('
                          else:
                              inserts[start] = '('
                          inserts[end] = ')'
                      for i in range(start + 1, end):
                          inserts[i] = '|'
  
          # collect all actions format strings
          parts = []
          for i, action in enumerate(actions):
  
              # suppressed arguments are marked with None
              # remove | separators for suppressed arguments
              if action.help is SUPPRESS:
                  parts.append(None)
                  if inserts.get(i) == '|':
                      inserts.pop(i)
                  elif inserts.get(i + 1) == '|':
                      inserts.pop(i + 1)
  
              # produce all arg strings
              elif not action.option_strings:
                  default = self._get_default_metavar_for_positional(action)
                  part = self._format_args(action, default)
  
                  # if it's in a group, strip the outer []
                  if action in group_actions:
                      if part[0] == '[' and part[-1] == ']':
                          part = part[1:-1]
  
                  # add the action string to the list
                  parts.append(part)
  
              # produce the first way to invoke the option in brackets
              else:
                  option_string = action.option_strings[0]
  
                  # if the Optional doesn't take a value, format is:
                  #    -s or --long
                  if action.nargs == 0:
                      part = '%s' % option_string
  
                  # if the Optional takes a value, format is:
                  #    -s ARGS or --long ARGS
                  else:
                      default = self._get_default_metavar_for_optional(action)
                      args_string = self._format_args(action, default)
                      part = '%s %s' % (option_string, args_string)
  
                  # make it look optional if it's not required or in a group
                  if not action.required and action not in group_actions:
                      part = '[%s]' % part
  
                  # add the action string to the list
                  parts.append(part)
  
          # insert things at the necessary indices
          for i in sorted(inserts, reverse=True):
              parts[i:i] = [inserts[i]]
  
          # join all the action items with spaces
          text = ' '.join([item for item in parts if item is not None])
  
          # clean up separators for mutually exclusive groups
          open = r'[\[(]'
          close = r'[\])]'
          text = _re.sub(r'(%s) ' % open, r'\1', text)
          text = _re.sub(r' (%s)' % close, r'\1', text)
          text = _re.sub(r'%s *%s' % (open, close), r'', text)
          text = _re.sub(r'\(([^|]*)\)', r'\1', text)
          text = text.strip()
  
          # return the text
          return text
  
      def _format_text(self, text):
          if '%(prog)' in text:
              text = text % dict(prog=self._prog)
          text_width = max(self._width - self._current_indent, 11)
          indent = ' ' * self._current_indent
          return self._fill_text(text, text_width, indent) + '\n\n'
  
      def _format_action(self, action):
          # determine the required width and the entry label
          help_position = min(self._action_max_length + 2,
                              self._max_help_position)
          help_width = max(self._width - help_position, 11)
          action_width = help_position - self._current_indent - 2
          action_header = self._format_action_invocation(action)
  
          # no help; start on same line and add a final newline
          if not action.help:
              tup = self._current_indent, '', action_header
              action_header = '%*s%s\n' % tup
  
          # short action name; start on the same line and pad two spaces
          elif len(action_header) <= action_width:
              tup = self._current_indent, '', action_width, action_header
              action_header = '%*s%-*s  ' % tup
              indent_first = 0
  
          # long action name; start on the next line
          else:
              tup = self._current_indent, '', action_header
              action_header = '%*s%s\n' % tup
              indent_first = help_position
  
          # collect the pieces of the action help
          parts = [action_header]
  
          # if there was help for the action, add lines of help text
          if action.help:
              help_text = self._expand_help(action)
              help_lines = self._split_lines(help_text, help_width)
              parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
              for line in help_lines[1:]:
                  parts.append('%*s%s\n' % (help_position, '', line))
  
          # or add a newline if the description doesn't end with one
          elif not action_header.endswith('\n'):
              parts.append('\n')
  
          # if there are any sub-actions, add their help as well
          for subaction in self._iter_indented_subactions(action):
              parts.append(self._format_action(subaction))
  
          # return a single string
          return self._join_parts(parts)
  
      def _format_action_invocation(self, action):
          if not action.option_strings:
              default = self._get_default_metavar_for_positional(action)
              metavar, = self._metavar_formatter(action, default)(1)
              return metavar
  
          else:
              parts = []
  
              # if the Optional doesn't take a value, format is:
              #    -s, --long
              if action.nargs == 0:
                  parts.extend(action.option_strings)
  
              # if the Optional takes a value, format is:
              #    -s ARGS, --long ARGS
              else:
                  default = self._get_default_metavar_for_optional(action)
                  args_string = self._format_args(action, default)
                  for option_string in action.option_strings:
                      parts.append('%s %s' % (option_string, args_string))
  
              return ', '.join(parts)
  
      def _metavar_formatter(self, action, default_metavar):
          if action.metavar is not None:
              result = action.metavar
          elif action.choices is not None:
              choice_strs = [str(choice) for choice in action.choices]
              result = '{%s}' % ','.join(choice_strs)
          else:
              result = default_metavar
  
          def format(tuple_size):
              if isinstance(result, tuple):
                  return result
              else:
                  return (result, ) * tuple_size
          return format
  
      def _format_args(self, action, default_metavar):
          get_metavar = self._metavar_formatter(action, default_metavar)
          if action.nargs is None:
              result = '%s' % get_metavar(1)
          elif action.nargs == OPTIONAL:
              result = '[%s]' % get_metavar(1)
          elif action.nargs == ZERO_OR_MORE:
              result = '[%s [%s ...]]' % get_metavar(2)
          elif action.nargs == ONE_OR_MORE:
              result = '%s [%s ...]' % get_metavar(2)
          elif action.nargs == REMAINDER:
              result = '...'
          elif action.nargs == PARSER:
              result = '%s ...' % get_metavar(1)
          else:
              formats = ['%s' for _ in range(action.nargs)]
              result = ' '.join(formats) % get_metavar(action.nargs)
          return result
  
      def _expand_help(self, action):
          params = dict(vars(action), prog=self._prog)
          for name in list(params):
              if params[name] is SUPPRESS:
                  del params[name]
          for name in list(params):
              if hasattr(params[name], '__name__'):
                  params[name] = params[name].__name__
          if params.get('choices') is not None:
              choices_str = ', '.join([str(c) for c in params['choices']])
              params['choices'] = choices_str
          return self._get_help_string(action) % params
  
      def _iter_indented_subactions(self, action):
          try:
              get_subactions = action._get_subactions
          except AttributeError:
              pass
          else:
              self._indent()
              yield from get_subactions()
              self._dedent()
  
      def _split_lines(self, text, width):
          text = self._whitespace_matcher.sub(' ', text).strip()
          return _textwrap.wrap(text, width)
  
      def _fill_text(self, text, width, indent):
          text = self._whitespace_matcher.sub(' ', text).strip()
          return _textwrap.fill(text, width, initial_indent=indent,
                                             subsequent_indent=indent)
  
      def _get_help_string(self, action):
          return action.help
  
      def _get_default_metavar_for_optional(self, action):
          return action.dest.upper()
  
      def _get_default_metavar_for_positional(self, action):
          return action.dest
  
  
  class RawDescriptionHelpFormatter(HelpFormatter):
      """Help message formatter which retains any formatting in descriptions.
  
      Only the name of this class is considered a public API. All the methods
      provided by the class are considered an implementation detail.
      """
  
      def _fill_text(self, text, width, indent):
          return ''.join(indent + line for line in text.splitlines(keepends=True))
  
  
  class RawTextHelpFormatter(RawDescriptionHelpFormatter):
      """Help message formatter which retains formatting of all help text.
  
      Only the name of this class is considered a public API. All the methods
      provided by the class are considered an implementation detail.
      """
  
      def _split_lines(self, text, width):
          return text.splitlines()
  
  
  class ArgumentDefaultsHelpFormatter(HelpFormatter):
      """Help message formatter which adds default values to argument help.
  
      Only the name of this class is considered a public API. All the methods
      provided by the class are considered an implementation detail.
      """
  
      def _get_help_string(self, action):
          help = action.help
          if '%(default)' not in action.help:
              if action.default is not SUPPRESS:
                  defaulting_nargs = [OPTIONAL, ZERO_OR_MORE]
                  if action.option_strings or action.nargs in defaulting_nargs:
                      help += ' (default: %(default)s)'
          return help
  
  
  class MetavarTypeHelpFormatter(HelpFormatter):
      """Help message formatter which uses the argument 'type' as the default
      metavar value (instead of the argument 'dest')
  
      Only the name of this class is considered a public API. All the methods
      provided by the class are considered an implementation detail.
      """
  
      def _get_default_metavar_for_optional(self, action):
          return action.type.__name__
  
      def _get_default_metavar_for_positional(self, action):
          return action.type.__name__
  
  
  
  # =====================
  # Options and Arguments
  # =====================
  
  def _get_action_name(argument):
      if argument is None:
          return None
      elif argument.option_strings:
          return  '/'.join(argument.option_strings)
      elif argument.metavar not in (None, SUPPRESS):
          return argument.metavar
      elif argument.dest not in (None, SUPPRESS):
          return argument.dest
      else:
          return None
  
  
  class ArgumentError(Exception):
      """An error from creating or using an argument (optional or positional).
  
      The string value of this exception is the message, augmented with
      information about the argument that caused it.
      """
  
      def __init__(self, argument, message):
          self.argument_name = _get_action_name(argument)
          self.message = message
  
      def __str__(self):
          if self.argument_name is None:
              format = '%(message)s'
          else:
              format = 'argument %(argument_name)s: %(message)s'
          return format % dict(message=self.message,
                               argument_name=self.argument_name)
  
  
  class ArgumentTypeError(Exception):
      """An error from trying to convert a command line string to a type."""
      pass
  
  
  # ==============
  # Action classes
  # ==============
  
  class Action(_AttributeHolder):
      """Information about how to convert command line strings to Python objects.
  
      Action objects are used by an ArgumentParser to represent the information
      needed to parse a single argument from one or more strings from the
      command line. The keyword arguments to the Action constructor are also
      all attributes of Action instances.
  
      Keyword Arguments:
  
          - option_strings -- A list of command-line option strings which
              should be associated with this action.
  
          - dest -- The name of the attribute to hold the created object(s)
  
          - nargs -- The number of command-line arguments that should be
              consumed. By default, one argument will be consumed and a single
              value will be produced.  Other values include:
                  - N (an integer) consumes N arguments (and produces a list)
                  - '?' consumes zero or one arguments
                  - '*' consumes zero or more arguments (and produces a list)
                  - '+' consumes one or more arguments (and produces a list)
              Note that the difference between the default and nargs=1 is that
              with the default, a single value will be produced, while with
              nargs=1, a list containing a single value will be produced.
  
          - const -- The value to be produced if the option is specified and the
              option uses an action that takes no values.
  
          - default -- The value to be produced if the option is not specified.
  
          - type -- A callable that accepts a single string argument, and
              returns the converted value.  The standard Python types str, int,
              float, and complex are useful examples of such callables.  If None,
              str is used.
  
          - choices -- A container of values that should be allowed. If not None,
              after a command-line argument has been converted to the appropriate
              type, an exception will be raised if it is not a member of this
              collection.
  
          - required -- True if the action must always be specified at the
              command line. This is only meaningful for optional command-line
              arguments.
  
          - help -- The help string describing the argument.
  
          - metavar -- The name to be used for the option's argument with the
              help string. If None, the 'dest' value will be used as the name.
      """
  
      def __init__(self,
                   option_strings,
                   dest,
                   nargs=None,
                   const=None,
                   default=None,
                   type=None,
                   choices=None,
                   required=False,
                   help=None,
                   metavar=None):
          self.option_strings = option_strings
          self.dest = dest
          self.nargs = nargs
          self.const = const
          self.default = default
          self.type = type
          self.choices = choices
          self.required = required
          self.help = help
          self.metavar = metavar
  
      def _get_kwargs(self):
          names = [
              'option_strings',
              'dest',
              'nargs',
              'const',
              'default',
              'type',
              'choices',
              'help',
              'metavar',
          ]
          return [(name, getattr(self, name)) for name in names]
  
      def __call__(self, parser, namespace, values, option_string=None):
          raise NotImplementedError(_('.__call__() not defined'))
  
  
  class _StoreAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest,
                   nargs=None,
                   const=None,
                   default=None,
                   type=None,
                   choices=None,
                   required=False,
                   help=None,
                   metavar=None):
          if nargs == 0:
              raise ValueError('nargs for store actions must be > 0; if you '
                               'have nothing to store, actions such as store '
                               'true or store const may be more appropriate')
          if const is not None and nargs != OPTIONAL:
              raise ValueError('nargs must be %r to supply const' % OPTIONAL)
          super(_StoreAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=nargs,
              const=const,
              default=default,
              type=type,
              choices=choices,
              required=required,
              help=help,
              metavar=metavar)
  
      def __call__(self, parser, namespace, values, option_string=None):
          setattr(namespace, self.dest, values)
  
  
  class _StoreConstAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest,
                   const,
                   default=None,
                   required=False,
                   help=None,
                   metavar=None):
          super(_StoreConstAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=0,
              const=const,
              default=default,
              required=required,
              help=help)
  
      def __call__(self, parser, namespace, values, option_string=None):
          setattr(namespace, self.dest, self.const)
  
  
  class _StoreTrueAction(_StoreConstAction):
  
      def __init__(self,
                   option_strings,
                   dest,
                   default=False,
                   required=False,
                   help=None):
          super(_StoreTrueAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              const=True,
              default=default,
              required=required,
              help=help)
  
  
  class _StoreFalseAction(_StoreConstAction):
  
      def __init__(self,
                   option_strings,
                   dest,
                   default=True,
                   required=False,
                   help=None):
          super(_StoreFalseAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              const=False,
              default=default,
              required=required,
              help=help)
  
  
  class _AppendAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest,
                   nargs=None,
                   const=None,
                   default=None,
                   type=None,
                   choices=None,
                   required=False,
                   help=None,
                   metavar=None):
          if nargs == 0:
              raise ValueError('nargs for append actions must be > 0; if arg '
                               'strings are not supplying the value to append, '
                               'the append const action may be more appropriate')
          if const is not None and nargs != OPTIONAL:
              raise ValueError('nargs must be %r to supply const' % OPTIONAL)
          super(_AppendAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=nargs,
              const=const,
              default=default,
              type=type,
              choices=choices,
              required=required,
              help=help,
              metavar=metavar)
  
      def __call__(self, parser, namespace, values, option_string=None):
          items = _copy.copy(_ensure_value(namespace, self.dest, []))
          items.append(values)
          setattr(namespace, self.dest, items)
  
  
  class _AppendConstAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest,
                   const,
                   default=None,
                   required=False,
                   help=None,
                   metavar=None):
          super(_AppendConstAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=0,
              const=const,
              default=default,
              required=required,
              help=help,
              metavar=metavar)
  
      def __call__(self, parser, namespace, values, option_string=None):
          items = _copy.copy(_ensure_value(namespace, self.dest, []))
          items.append(self.const)
          setattr(namespace, self.dest, items)
  
  
  class _CountAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest,
                   default=None,
                   required=False,
                   help=None):
          super(_CountAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=0,
              default=default,
              required=required,
              help=help)
  
      def __call__(self, parser, namespace, values, option_string=None):
          new_count = _ensure_value(namespace, self.dest, 0) + 1
          setattr(namespace, self.dest, new_count)
  
  
  class _HelpAction(Action):
  
      def __init__(self,
                   option_strings,
                   dest=SUPPRESS,
                   default=SUPPRESS,
                   help=None):
          super(_HelpAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              default=default,
              nargs=0,
              help=help)
  
      def __call__(self, parser, namespace, values, option_string=None):
          parser.print_help()
          parser.exit()
  
  
  class _VersionAction(Action):
  
      def __init__(self,
                   option_strings,
                   version=None,
                   dest=SUPPRESS,
                   default=SUPPRESS,
                   help="show program's version number and exit"):
          super(_VersionAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              default=default,
              nargs=0,
              help=help)
          self.version = version
  
      def __call__(self, parser, namespace, values, option_string=None):
          version = self.version
          if version is None:
              version = parser.version
          formatter = parser._get_formatter()
          formatter.add_text(version)
          parser._print_message(formatter.format_help(), _sys.stdout)
          parser.exit()
  
  
  class _SubParsersAction(Action):
  
      class _ChoicesPseudoAction(Action):
  
          def __init__(self, name, aliases, help):
              metavar = dest = name
              if aliases:
                  metavar += ' (%s)' % ', '.join(aliases)
              sup = super(_SubParsersAction._ChoicesPseudoAction, self)
              sup.__init__(option_strings=[], dest=dest, help=help,
                           metavar=metavar)
  
      def __init__(self,
                   option_strings,
                   prog,
                   parser_class,
                   dest=SUPPRESS,
                   help=None,
                   metavar=None):
  
          self._prog_prefix = prog
          self._parser_class = parser_class
          self._name_parser_map = _collections.OrderedDict()
          self._choices_actions = []
  
          super(_SubParsersAction, self).__init__(
              option_strings=option_strings,
              dest=dest,
              nargs=PARSER,
              choices=self._name_parser_map,
              help=help,
              metavar=metavar)
  
      def add_parser(self, name, **kwargs):
          # set prog from the existing prefix
          if kwargs.get('prog') is None:
              kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
  
          aliases = kwargs.pop('aliases', ())
  
          # create a pseudo-action to hold the choice help
          if 'help' in kwargs:
              help = kwargs.pop('help')
              choice_action = self._ChoicesPseudoAction(name, aliases, help)
              self._choices_actions.append(choice_action)
  
          # create the parser and add it to the map
          parser = self._parser_class(**kwargs)
          self._name_parser_map[name] = parser
  
          # make parser available under aliases also
          for alias in aliases:
              self._name_parser_map[alias] = parser
  
          return parser
  
      def _get_subactions(self):
          return self._choices_actions
  
      def __call__(self, parser, namespace, values, option_string=None):
          parser_name = values[0]
          arg_strings = values[1:]
  
          # set the parser name if requested
          if self.dest is not SUPPRESS:
              setattr(namespace, self.dest, parser_name)
  
          # select the parser
          try:
              parser = self._name_parser_map[parser_name]
          except KeyError:
              args = {'parser_name': parser_name,
                      'choices': ', '.join(self._name_parser_map)}
              msg = _('unknown parser %(parser_name)r (choices: %(choices)s)') % args
              raise ArgumentError(self, msg)
  
          # parse all the remaining options into the namespace
          # store any unrecognized options on the object, so that the top
          # level parser can decide what to do with them
  
          # In case this subparser defines new defaults, we parse them
          # in a new namespace object and then update the original
          # namespace for the relevant parts.
          subnamespace, arg_strings = parser.parse_known_args(arg_strings, None)
          for key, value in vars(subnamespace).items():
              setattr(namespace, key, value)
  
          if arg_strings:
              vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, [])
              getattr(namespace, _UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
  
  
  # ==============
  # Type classes
  # ==============
  
  class FileType(object):
      """Factory for creating file object types
  
      Instances of FileType are typically passed as type= arguments to the
      ArgumentParser add_argument() method.
  
      Keyword Arguments:
          - mode -- A string indicating how the file is to be opened. Accepts the
              same values as the builtin open() function.
          - bufsize -- The file's desired buffer size. Accepts the same values as
              the builtin open() function.
          - encoding -- The file's encoding. Accepts the same values as the
              builtin open() function.
          - errors -- A string indicating how encoding and decoding errors are to
              be handled. Accepts the same value as the builtin open() function.
      """
  
      def __init__(self, mode='r', bufsize=-1, encoding=None, errors=None):
          self._mode = mode
          self._bufsize = bufsize
          self._encoding = encoding
          self._errors = errors
  
      def __call__(self, string):
          # the special argument "-" means sys.std{in,out}
          if string == '-':
              if 'r' in self._mode:
                  return _sys.stdin
              elif 'w' in self._mode:
                  return _sys.stdout
              else:
                  msg = _('argument "-" with mode %r') % self._mode
                  raise ValueError(msg)
  
          # all other arguments are used as file names
          try:
              return open(string, self._mode, self._bufsize, self._encoding,
                          self._errors)
          except OSError as e:
              message = _("can't open '%s': %s")
              raise ArgumentTypeError(message % (string, e))
  
      def __repr__(self):
          args = self._mode, self._bufsize
          kwargs = [('encoding', self._encoding), ('errors', self._errors)]
          args_str = ', '.join([repr(arg) for arg in args if arg != -1] +
                               ['%s=%r' % (kw, arg) for kw, arg in kwargs
                                if arg is not None])
          return '%s(%s)' % (type(self).__name__, args_str)
  
  # ===========================
  # Optional and Positional Parsing
  # ===========================
  
  class Namespace(_AttributeHolder):
      """Simple object for storing attributes.
  
      Implements equality by attribute names and values, and provides a simple
      string representation.
      """
  
      def __init__(self, **kwargs):
          for name in kwargs:
              setattr(self, name, kwargs[name])
  
      def __eq__(self, other):
          if not isinstance(other, Namespace):
              return NotImplemented
          return vars(self) == vars(other)
  
      def __contains__(self, key):
          return key in self.__dict__
  
  
  class _ActionsContainer(object):
  
      def __init__(self,
                   description,
                   prefix_chars,
                   argument_default,
                   conflict_handler):
          super(_ActionsContainer, self).__init__()
  
          self.description = description
          self.argument_default = argument_default
          self.prefix_chars = prefix_chars
          self.conflict_handler = conflict_handler
  
          # set up registries
          self._registries = {}
  
          # register actions
          self.register('action', None, _StoreAction)
          self.register('action', 'store', _StoreAction)
          self.register('action', 'store_const', _StoreConstAction)
          self.register('action', 'store_true', _StoreTrueAction)
          self.register('action', 'store_false', _StoreFalseAction)
          self.register('action', 'append', _AppendAction)
          self.register('action', 'append_const', _AppendConstAction)
          self.register('action', 'count', _CountAction)
          self.register('action', 'help', _HelpAction)
          self.register('action', 'version', _VersionAction)
          self.register('action', 'parsers', _SubParsersAction)
  
          # raise an exception if the conflict handler is invalid
          self._get_handler()
  
          # action storage
          self._actions = []
          self._option_string_actions = {}
  
          # groups
          self._action_groups = []
          self._mutually_exclusive_groups = []
  
          # defaults storage
          self._defaults = {}
  
          # determines whether an "option" looks like a negative number
          self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')
  
          # whether or not there are any optionals that look like negative
          # numbers -- uses a list so it can be shared and edited
          self._has_negative_number_optionals = []
  
      # ====================
      # Registration methods
      # ====================
      def register(self, registry_name, value, object):
          registry = self._registries.setdefault(registry_name, {})
          registry[value] = object
  
      def _registry_get(self, registry_name, value, default=None):
          return self._registries[registry_name].get(value, default)
  
      # ==================================
      # Namespace default accessor methods
      # ==================================
      def set_defaults(self, **kwargs):
          self._defaults.update(kwargs)
  
          # if these defaults match any existing arguments, replace
          # the previous default on the object with the new one
          for action in self._actions:
              if action.dest in kwargs:
                  action.default = kwargs[action.dest]
  
      def get_default(self, dest):
          for action in self._actions:
              if action.dest == dest and action.default is not None:
                  return action.default
          return self._defaults.get(dest, None)
  
  
      # =======================
      # Adding argument actions
      # =======================
      def add_argument(self, *args, **kwargs):
          """
          add_argument(dest, ..., name=value, ...)
          add_argument(option_string, option_string, ..., name=value, ...)
          """
  
          # if no positional args are supplied or only one is supplied and
          # it doesn't look like an option string, parse a positional
          # argument
          chars = self.prefix_chars
          if not args or len(args) == 1 and args[0][0] not in chars:
              if args and 'dest' in kwargs:
                  raise ValueError('dest supplied twice for positional argument')
              kwargs = self._get_positional_kwargs(*args, **kwargs)
  
          # otherwise, we're adding an optional argument
          else:
              kwargs = self._get_optional_kwargs(*args, **kwargs)
  
          # if no default was supplied, use the parser-level default
          if 'default' not in kwargs:
              dest = kwargs['dest']
              if dest in self._defaults:
                  kwargs['default'] = self._defaults[dest]
              elif self.argument_default is not None:
                  kwargs['default'] = self.argument_default
  
          # create the action object, and add it to the parser
          action_class = self._pop_action_class(kwargs)
          if not callable(action_class):
              raise ValueError('unknown action "%s"' % (action_class,))
          action = action_class(**kwargs)
  
          # raise an error if the action type is not callable
          type_func = self._registry_get('type', action.type, action.type)
          if not callable(type_func):
              raise ValueError('%r is not callable' % (type_func,))
  
          # raise an error if the metavar does not match the type
          if hasattr(self, "_get_formatter"):
              try:
                  self._get_formatter()._format_args(action, None)
              except TypeError:
                  raise ValueError("length of metavar tuple does not match nargs")
  
          return self._add_action(action)
  
      def add_argument_group(self, *args, **kwargs):
          group = _ArgumentGroup(self, *args, **kwargs)
          self._action_groups.append(group)
          return group
  
      def add_mutually_exclusive_group(self, **kwargs):
          group = _MutuallyExclusiveGroup(self, **kwargs)
          self._mutually_exclusive_groups.append(group)
          return group
  
      def _add_action(self, action):
          # resolve any conflicts
          self._check_conflict(action)
  
          # add to actions list
          self._actions.append(action)
          action.container = self
  
          # index the action by any option strings it has
          for option_string in action.option_strings:
              self._option_string_actions[option_string] = action
  
          # set the flag if any option strings look like negative numbers
          for option_string in action.option_strings:
              if self._negative_number_matcher.match(option_string):
                  if not self._has_negative_number_optionals:
                      self._has_negative_number_optionals.append(True)
  
          # return the created action
          return action
  
      def _remove_action(self, action):
          self._actions.remove(action)
  
      def _add_container_actions(self, container):
          # collect groups by titles
          title_group_map = {}
          for group in self._action_groups:
              if group.title in title_group_map:
                  msg = _('cannot merge actions - two groups are named %r')
                  raise ValueError(msg % (group.title))
              title_group_map[group.title] = group
  
          # map each action to its group
          group_map = {}
          for group in container._action_groups:
  
              # if a group with the title exists, use that, otherwise
              # create a new group matching the container's group
              if group.title not in title_group_map:
                  title_group_map[group.title] = self.add_argument_group(
                      title=group.title,
                      description=group.description,
                      conflict_handler=group.conflict_handler)
  
              # map the actions to their new group
              for action in group._group_actions:
                  group_map[action] = title_group_map[group.title]
  
          # add container's mutually exclusive groups
          # NOTE: if add_mutually_exclusive_group ever gains title= and
          # description= then this code will need to be expanded as above
          for group in container._mutually_exclusive_groups:
              mutex_group = self.add_mutually_exclusive_group(
                  required=group.required)
  
              # map the actions to their new mutex group
              for action in group._group_actions:
                  group_map[action] = mutex_group
  
          # add all actions to this container or their group
          for action in container._actions:
              group_map.get(action, self)._add_action(action)
  
      def _get_positional_kwargs(self, dest, **kwargs):
          # make sure required is not specified
          if 'required' in kwargs:
              msg = _("'required' is an invalid argument for positionals")
              raise TypeError(msg)
  
          # mark positional arguments as required if at least one is
          # always required
          if kwargs.get('nargs') not in [OPTIONAL, ZERO_OR_MORE]:
              kwargs['required'] = True
          if kwargs.get('nargs') == ZERO_OR_MORE and 'default' not in kwargs:
              kwargs['required'] = True
  
          # return the keyword arguments with no option strings
          return dict(kwargs, dest=dest, option_strings=[])
  
      def _get_optional_kwargs(self, *args, **kwargs):
          # determine short and long option strings
          option_strings = []
          long_option_strings = []
          for option_string in args:
              # error on strings that don't start with an appropriate prefix
              if not option_string[0] in self.prefix_chars:
                  args = {'option': option_string,
                          'prefix_chars': self.prefix_chars}
                  msg = _('invalid option string %(option)r: '
                          'must start with a character %(prefix_chars)r')
                  raise ValueError(msg % args)
  
              # strings starting with two prefix characters are long options
              option_strings.append(option_string)
              if option_string[0] in self.prefix_chars:
                  if len(option_string) > 1:
                      if option_string[1] in self.prefix_chars:
                          long_option_strings.append(option_string)
  
          # infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x'
          dest = kwargs.pop('dest', None)
          if dest is None:
              if long_option_strings:
                  dest_option_string = long_option_strings[0]
              else:
                  dest_option_string = option_strings[0]
              dest = dest_option_string.lstrip(self.prefix_chars)
              if not dest:
                  msg = _('dest= is required for options like %r')
                  raise ValueError(msg % option_string)
              dest = dest.replace('-', '_')
  
          # return the updated keyword arguments
          return dict(kwargs, dest=dest, option_strings=option_strings)
  
      def _pop_action_class(self, kwargs, default=None):
          action = kwargs.pop('action', default)
          return self._registry_get('action', action, action)
  
      def _get_handler(self):
          # determine function from conflict handler string
          handler_func_name = '_handle_conflict_%s' % self.conflict_handler
          try:
              return getattr(self, handler_func_name)
          except AttributeError:
              msg = _('invalid conflict_resolution value: %r')
              raise ValueError(msg % self.conflict_handler)
  
      def _check_conflict(self, action):
  
          # find all options that conflict with this option
          confl_optionals = []
          for option_string in action.option_strings:
              if option_string in self._option_string_actions:
                  confl_optional = self._option_string_actions[option_string]
                  confl_optionals.append((option_string, confl_optional))
  
          # resolve any conflicts
          if confl_optionals:
              conflict_handler = self._get_handler()
              conflict_handler(action, confl_optionals)
  
      def _handle_conflict_error(self, action, conflicting_actions):
          message = ngettext('conflicting option string: %s',
                             'conflicting option strings: %s',
                             len(conflicting_actions))
          conflict_string = ', '.join([option_string
                                       for option_string, action
                                       in conflicting_actions])
          raise ArgumentError(action, message % conflict_string)
  
      def _handle_conflict_resolve(self, action, conflicting_actions):
  
          # remove all conflicting options
          for option_string, action in conflicting_actions:
  
              # remove the conflicting option
              action.option_strings.remove(option_string)
              self._option_string_actions.pop(option_string, None)
  
              # if the option now has no option string, remove it from the
              # container holding it
              if not action.option_strings:
                  action.container._remove_action(action)
  
  
  class _ArgumentGroup(_ActionsContainer):
  
      def __init__(self, container, title=None, description=None, **kwargs):
          # add any missing keyword arguments by checking the container
          update = kwargs.setdefault
          update('conflict_handler', container.conflict_handler)
          update('prefix_chars', container.prefix_chars)
          update('argument_default', container.argument_default)
          super_init = super(_ArgumentGroup, self).__init__
          super_init(description=description, **kwargs)
  
          # group attributes
          self.title = title
          self._group_actions = []
  
          # share most attributes with the container
          self._registries = container._registries
          self._actions = container._actions
          self._option_string_actions = container._option_string_actions
          self._defaults = container._defaults
          self._has_negative_number_optionals = \
              container._has_negative_number_optionals
          self._mutually_exclusive_groups = container._mutually_exclusive_groups
  
      def _add_action(self, action):
          action = super(_ArgumentGroup, self)._add_action(action)
          self._group_actions.append(action)
          return action
  
      def _remove_action(self, action):
          super(_ArgumentGroup, self)._remove_action(action)
          self._group_actions.remove(action)
  
  
  class _MutuallyExclusiveGroup(_ArgumentGroup):
  
      def __init__(self, container, required=False):
          super(_MutuallyExclusiveGroup, self).__init__(container)
          self.required = required
          self._container = container
  
      def _add_action(self, action):
          if action.required:
              msg = _('mutually exclusive arguments must be optional')
              raise ValueError(msg)
          action = self._container._add_action(action)
          self._group_actions.append(action)
          return action
  
      def _remove_action(self, action):
          self._container._remove_action(action)
          self._group_actions.remove(action)
  
  
  class ArgumentParser(_AttributeHolder, _ActionsContainer):
      """Object for parsing command line strings into Python objects.
  
      Keyword Arguments:
          - prog -- The name of the program (default: sys.argv[0])
          - usage -- A usage message (default: auto-generated from arguments)
          - description -- A description of what the program does
          - epilog -- Text following the argument descriptions
          - parents -- Parsers whose arguments should be copied into this one
          - formatter_class -- HelpFormatter class for printing help messages
          - prefix_chars -- Characters that prefix optional arguments
          - fromfile_prefix_chars -- Characters that prefix files containing
              additional arguments
          - argument_default -- The default value for all arguments
          - conflict_handler -- String indicating how to handle conflicts
          - add_help -- Add a -h/-help option
          - allow_abbrev -- Allow long options to be abbreviated unambiguously
      """
  
      def __init__(self,
                   prog=None,
                   usage=None,
                   description=None,
                   epilog=None,
                   parents=[],
                   formatter_class=HelpFormatter,
                   prefix_chars='-',
                   fromfile_prefix_chars=None,
                   argument_default=None,
                   conflict_handler='error',
                   add_help=True,
                   allow_abbrev=True):
  
          superinit = super(ArgumentParser, self).__init__
          superinit(description=description,
                    prefix_chars=prefix_chars,
                    argument_default=argument_default,
                    conflict_handler=conflict_handler)
  
          # default setting for prog
          if prog is None:
              prog = _os.path.basename(_sys.argv[0])
  
          self.prog = prog
          self.usage = usage
          self.epilog = epilog
          self.formatter_class = formatter_class
          self.fromfile_prefix_chars = fromfile_prefix_chars
          self.add_help = add_help
          self.allow_abbrev = allow_abbrev
  
          add_group = self.add_argument_group
          self._positionals = add_group(_('positional arguments'))
          self._optionals = add_group(_('optional arguments'))
          self._subparsers = None
  
          # register types
          def identity(string):
              return string
          self.register('type', None, identity)
  
          # add help argument if necessary
          # (using explicit default to override global argument_default)
          default_prefix = '-' if '-' in prefix_chars else prefix_chars[0]
          if self.add_help:
              self.add_argument(
                  default_prefix+'h', default_prefix*2+'help',
                  action='help', default=SUPPRESS,
                  help=_('show this help message and exit'))
  
          # add parent arguments and defaults
          for parent in parents:
              self._add_container_actions(parent)
              try:
                  defaults = parent._defaults
              except AttributeError:
                  pass
              else:
                  self._defaults.update(defaults)
  
      # =======================
      # Pretty __repr__ methods
      # =======================
      def _get_kwargs(self):
          names = [
              'prog',
              'usage',
              'description',
              'formatter_class',
              'conflict_handler',
              'add_help',
          ]
          return [(name, getattr(self, name)) for name in names]
  
      # ==================================
      # Optional/Positional adding methods
      # ==================================
      def add_subparsers(self, **kwargs):
          if self._subparsers is not None:
              self.error(_('cannot have multiple subparser arguments'))
  
          # add the parser class to the arguments if it's not present
          kwargs.setdefault('parser_class', type(self))
  
          if 'title' in kwargs or 'description' in kwargs:
              title = _(kwargs.pop('title', 'subcommands'))
              description = _(kwargs.pop('description', None))
              self._subparsers = self.add_argument_group(title, description)
          else:
              self._subparsers = self._positionals
  
          # prog defaults to the usage message of this parser, skipping
          # optional arguments and with no "usage:" prefix
          if kwargs.get('prog') is None:
              formatter = self._get_formatter()
              positionals = self._get_positional_actions()
              groups = self._mutually_exclusive_groups
              formatter.add_usage(self.usage, positionals, groups, '')
              kwargs['prog'] = formatter.format_help().strip()
  
          # create the parsers action and add it to the positionals list
          parsers_class = self._pop_action_class(kwargs, 'parsers')
          action = parsers_class(option_strings=[], **kwargs)
          self._subparsers._add_action(action)
  
          # return the created parsers action
          return action
  
      def _add_action(self, action):
          if action.option_strings:
              self._optionals._add_action(action)
          else:
              self._positionals._add_action(action)
          return action
  
      def _get_optional_actions(self):
          return [action
                  for action in self._actions
                  if action.option_strings]
  
      def _get_positional_actions(self):
          return [action
                  for action in self._actions
                  if not action.option_strings]
  
      # =====================================
      # Command line argument parsing methods
      # =====================================
      def parse_args(self, args=None, namespace=None):
          args, argv = self.parse_known_args(args, namespace)
          if argv:
              msg = _('unrecognized arguments: %s')
              self.error(msg % ' '.join(argv))
          return args
  
      def parse_known_args(self, args=None, namespace=None):
          if args is None:
              # args default to the system args
              args = _sys.argv[1:]
          else:
              # make sure that args are mutable
              args = list(args)
  
          # default Namespace built from parser defaults
          if namespace is None:
              namespace = Namespace()
  
          # add any action defaults that aren't present
          for action in self._actions:
              if action.dest is not SUPPRESS:
                  if not hasattr(namespace, action.dest):
                      if action.default is not SUPPRESS:
                          setattr(namespace, action.dest, action.default)
  
          # add any parser defaults that aren't present
          for dest in self._defaults:
              if not hasattr(namespace, dest):
                  setattr(namespace, dest, self._defaults[dest])
  
          # parse the arguments and exit if there are any errors
          try:
              namespace, args = self._parse_known_args(args, namespace)
              if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR):
                  args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR))
                  delattr(namespace, _UNRECOGNIZED_ARGS_ATTR)
              return namespace, args
          except ArgumentError:
              err = _sys.exc_info()[1]
              self.error(str(err))
  
      def _parse_known_args(self, arg_strings, namespace):
          # replace arg strings that are file references
          if self.fromfile_prefix_chars is not None:
              arg_strings = self._read_args_from_files(arg_strings)
  
          # map all mutually exclusive arguments to the other arguments
          # they can't occur with
          action_conflicts = {}
          for mutex_group in self._mutually_exclusive_groups:
              group_actions = mutex_group._group_actions
              for i, mutex_action in enumerate(mutex_group._group_actions):
                  conflicts = action_conflicts.setdefault(mutex_action, [])
                  conflicts.extend(group_actions[:i])
                  conflicts.extend(group_actions[i + 1:])
  
          # find all option indices, and determine the arg_string_pattern
          # which has an 'O' if there is an option at an index,
          # an 'A' if there is an argument, or a '-' if there is a '--'
          option_string_indices = {}
          arg_string_pattern_parts = []
          arg_strings_iter = iter(arg_strings)
          for i, arg_string in enumerate(arg_strings_iter):
  
              # all args after -- are non-options
              if arg_string == '--':
                  arg_string_pattern_parts.append('-')
                  for arg_string in arg_strings_iter:
                      arg_string_pattern_parts.append('A')
  
              # otherwise, add the arg to the arg strings
              # and note the index if it was an option
              else:
                  option_tuple = self._parse_optional(arg_string)
                  if option_tuple is None:
                      pattern = 'A'
                  else:
                      option_string_indices[i] = option_tuple
                      pattern = 'O'
                  arg_string_pattern_parts.append(pattern)
  
          # join the pieces together to form the pattern
          arg_strings_pattern = ''.join(arg_string_pattern_parts)
  
          # converts arg strings to the appropriate and then takes the action
          seen_actions = set()
          seen_non_default_actions = set()
  
          def take_action(action, argument_strings, option_string=None):
              seen_actions.add(action)
              argument_values = self._get_values(action, argument_strings)
  
              # error if this argument is not allowed with other previously
              # seen arguments, assuming that actions that use the default
              # value don't really count as "present"
              if argument_values is not action.default:
                  seen_non_default_actions.add(action)
                  for conflict_action in action_conflicts.get(action, []):
                      if conflict_action in seen_non_default_actions:
                          msg = _('not allowed with argument %s')
                          action_name = _get_action_name(conflict_action)
                          raise ArgumentError(action, msg % action_name)
  
              # take the action if we didn't receive a SUPPRESS value
              # (e.g. from a default)
              if argument_values is not SUPPRESS:
                  action(self, namespace, argument_values, option_string)
  
          # function to convert arg_strings into an optional action
          def consume_optional(start_index):
  
              # get the optional identified at this index
              option_tuple = option_string_indices[start_index]
              action, option_string, explicit_arg = option_tuple
  
              # identify additional optionals in the same arg string
              # (e.g. -xyz is the same as -x -y -z if no args are required)
              match_argument = self._match_argument
              action_tuples = []
              while True:
  
                  # if we found no optional action, skip it
                  if action is None:
                      extras.append(arg_strings[start_index])
                      return start_index + 1
  
                  # if there is an explicit argument, try to match the
                  # optional's string arguments to only this
                  if explicit_arg is not None:
                      arg_count = match_argument(action, 'A')
  
                      # if the action is a single-dash option and takes no
                      # arguments, try to parse more single-dash options out
                      # of the tail of the option string
                      chars = self.prefix_chars
                      if arg_count == 0 and option_string[1] not in chars:
                          action_tuples.append((action, [], option_string))
                          char = option_string[0]
                          option_string = char + explicit_arg[0]
                          new_explicit_arg = explicit_arg[1:] or None
                          optionals_map = self._option_string_actions
                          if option_string in optionals_map:
                              action = optionals_map[option_string]
                              explicit_arg = new_explicit_arg
                          else:
                              msg = _('ignored explicit argument %r')
                              raise ArgumentError(action, msg % explicit_arg)
  
                      # if the action expect exactly one argument, we've
                      # successfully matched the option; exit the loop
                      elif arg_count == 1:
                          stop = start_index + 1
                          args = [explicit_arg]
                          action_tuples.append((action, args, option_string))
                          break
  
                      # error if a double-dash option did not use the
                      # explicit argument
                      else:
                          msg = _('ignored explicit argument %r')
                          raise ArgumentError(action, msg % explicit_arg)
  
                  # if there is no explicit argument, try to match the
                  # optional's string arguments with the following strings
                  # if successful, exit the loop
                  else:
                      start = start_index + 1
                      selected_patterns = arg_strings_pattern[start:]
                      arg_count = match_argument(action, selected_patterns)
                      stop = start + arg_count
                      args = arg_strings[start:stop]
                      action_tuples.append((action, args, option_string))
                      break
  
              # add the Optional to the list and return the index at which
              # the Optional's string args stopped
              assert action_tuples
              for action, args, option_string in action_tuples:
                  take_action(action, args, option_string)
              return stop
  
          # the list of Positionals left to be parsed; this is modified
          # by consume_positionals()
          positionals = self._get_positional_actions()
  
          # function to convert arg_strings into positional actions
          def consume_positionals(start_index):
              # match as many Positionals as possible
              match_partial = self._match_arguments_partial
              selected_pattern = arg_strings_pattern[start_index:]
              arg_counts = match_partial(positionals, selected_pattern)
  
              # slice off the appropriate arg strings for each Positional
              # and add the Positional and its args to the list
              for action, arg_count in zip(positionals, arg_counts):
                  args = arg_strings[start_index: start_index + arg_count]
                  start_index += arg_count
                  take_action(action, args)
  
              # slice off the Positionals that we just parsed and return the
              # index at which the Positionals' string args stopped
              positionals[:] = positionals[len(arg_counts):]
              return start_index
  
          # consume Positionals and Optionals alternately, until we have
          # passed the last option string
          extras = []
          start_index = 0
          if option_string_indices:
              max_option_string_index = max(option_string_indices)
          else:
              max_option_string_index = -1
          while start_index <= max_option_string_index:
  
              # consume any Positionals preceding the next option
              next_option_string_index = min([
                  index
                  for index in option_string_indices
                  if index >= start_index])
              if start_index != next_option_string_index:
                  positionals_end_index = consume_positionals(start_index)
  
                  # only try to parse the next optional if we didn't consume
                  # the option string during the positionals parsing
                  if positionals_end_index > start_index:
                      start_index = positionals_end_index
                      continue
                  else:
                      start_index = positionals_end_index
  
              # if we consumed all the positionals we could and we're not
              # at the index of an option string, there were extra arguments
              if start_index not in option_string_indices:
                  strings = arg_strings[start_index:next_option_string_index]
                  extras.extend(strings)
                  start_index = next_option_string_index
  
              # consume the next optional and any arguments for it
              start_index = consume_optional(start_index)
  
          # consume any positionals following the last Optional
          stop_index = consume_positionals(start_index)
  
          # if we didn't consume all the argument strings, there were extras
          extras.extend(arg_strings[stop_index:])
  
          # make sure all required actions were present and also convert
          # action defaults which were not given as arguments
          required_actions = []
          for action in self._actions:
              if action not in seen_actions:
                  if action.required:
                      required_actions.append(_get_action_name(action))
                  else:
                      # Convert action default now instead of doing it before
                      # parsing arguments to avoid calling convert functions
                      # twice (which may fail) if the argument was given, but
                      # only if it was defined already in the namespace
                      if (action.default is not None and
                          isinstance(action.default, str) and
                          hasattr(namespace, action.dest) and
                          action.default is getattr(namespace, action.dest)):
                          setattr(namespace, action.dest,
                                  self._get_value(action, action.default))
  
          if required_actions:
              self.error(_('the following arguments are required: %s') %
                         ', '.join(required_actions))
  
          # make sure all required groups had one option present
          for group in self._mutually_exclusive_groups:
              if group.required:
                  for action in group._group_actions:
                      if action in seen_non_default_actions:
                          break
  
                  # if no actions were used, report the error
                  else:
                      names = [_get_action_name(action)
                               for action in group._group_actions
                               if action.help is not SUPPRESS]
                      msg = _('one of the arguments %s is required')
                      self.error(msg % ' '.join(names))
  
          # return the updated namespace and the extra arguments
          return namespace, extras
  
      def _read_args_from_files(self, arg_strings):
          # expand arguments referencing files
          new_arg_strings = []
          for arg_string in arg_strings:
  
              # for regular arguments, just add them back into the list
              if not arg_string or arg_string[0] not in self.fromfile_prefix_chars:
                  new_arg_strings.append(arg_string)
  
              # replace arguments referencing files with the file content
              else:
                  try:
                      with open(arg_string[1:]) as args_file:
                          arg_strings = []
                          for arg_line in args_file.read().splitlines():
                              for arg in self.convert_arg_line_to_args(arg_line):
                                  arg_strings.append(arg)
                          arg_strings = self._read_args_from_files(arg_strings)
                          new_arg_strings.extend(arg_strings)
                  except OSError:
                      err = _sys.exc_info()[1]
                      self.error(str(err))
  
          # return the modified argument list
          return new_arg_strings
  
      def convert_arg_line_to_args(self, arg_line):
          return [arg_line]
  
      def _match_argument(self, action, arg_strings_pattern):
          # match the pattern for this action to the arg strings
          nargs_pattern = self._get_nargs_pattern(action)
          match = _re.match(nargs_pattern, arg_strings_pattern)
  
          # raise an exception if we weren't able to find a match
          if match is None:
              nargs_errors = {
                  None: _('expected one argument'),
                  OPTIONAL: _('expected at most one argument'),
                  ONE_OR_MORE: _('expected at least one argument'),
              }
              default = ngettext('expected %s argument',
                                 'expected %s arguments',
                                 action.nargs) % action.nargs
              msg = nargs_errors.get(action.nargs, default)
              raise ArgumentError(action, msg)
  
          # return the number of arguments matched
          return len(match.group(1))
  
      def _match_arguments_partial(self, actions, arg_strings_pattern):
          # progressively shorten the actions list by slicing off the
          # final actions until we find a match
          result = []
          for i in range(len(actions), 0, -1):
              actions_slice = actions[:i]
              pattern = ''.join([self._get_nargs_pattern(action)
                                 for action in actions_slice])
              match = _re.match(pattern, arg_strings_pattern)
              if match is not None:
                  result.extend([len(string) for string in match.groups()])
                  break
  
          # return the list of arg string counts
          return result
  
      def _parse_optional(self, arg_string):
          # if it's an empty string, it was meant to be a positional
          if not arg_string:
              return None
  
          # if it doesn't start with a prefix, it was meant to be positional
          if not arg_string[0] in self.prefix_chars:
              return None
  
          # if the option string is present in the parser, return the action
          if arg_string in self._option_string_actions:
              action = self._option_string_actions[arg_string]
              return action, arg_string, None
  
          # if it's just a single character, it was meant to be positional
          if len(arg_string) == 1:
              return None
  
          # if the option string before the "=" is present, return the action
          if '=' in arg_string:
              option_string, explicit_arg = arg_string.split('=', 1)
              if option_string in self._option_string_actions:
                  action = self._option_string_actions[option_string]
                  return action, option_string, explicit_arg
  
          if self.allow_abbrev:
              # search through all possible prefixes of the option string
              # and all actions in the parser for possible interpretations
              option_tuples = self._get_option_tuples(arg_string)
  
              # if multiple actions match, the option string was ambiguous
              if len(option_tuples) > 1:
                  options = ', '.join([option_string
                      for action, option_string, explicit_arg in option_tuples])
                  args = {'option': arg_string, 'matches': options}
                  msg = _('ambiguous option: %(option)s could match %(matches)s')
                  self.error(msg % args)
  
              # if exactly one action matched, this segmentation is good,
              # so return the parsed action
              elif len(option_tuples) == 1:
                  option_tuple, = option_tuples
                  return option_tuple
  
          # if it was not found as an option, but it looks like a negative
          # number, it was meant to be positional
          # unless there are negative-number-like options
          if self._negative_number_matcher.match(arg_string):
              if not self._has_negative_number_optionals:
                  return None
  
          # if it contains a space, it was meant to be a positional
          if ' ' in arg_string:
              return None
  
          # it was meant to be an optional but there is no such option
          # in this parser (though it might be a valid option in a subparser)
          return None, arg_string, None
  
      def _get_option_tuples(self, option_string):
          result = []
  
          # option strings starting with two prefix characters are only
          # split at the '='
          chars = self.prefix_chars
          if option_string[0] in chars and option_string[1] in chars:
              if '=' in option_string:
                  option_prefix, explicit_arg = option_string.split('=', 1)
              else:
                  option_prefix = option_string
                  explicit_arg = None
              for option_string in self._option_string_actions:
                  if option_string.startswith(option_prefix):
                      action = self._option_string_actions[option_string]
                      tup = action, option_string, explicit_arg
                      result.append(tup)
  
          # single character options can be concatenated with their arguments
          # but multiple character options always have to have their argument
          # separate
          elif option_string[0] in chars and option_string[1] not in chars:
              option_prefix = option_string
              explicit_arg = None
              short_option_prefix = option_string[:2]
              short_explicit_arg = option_string[2:]
  
              for option_string in self._option_string_actions:
                  if option_string == short_option_prefix:
                      action = self._option_string_actions[option_string]
                      tup = action, option_string, short_explicit_arg
                      result.append(tup)
                  elif option_string.startswith(option_prefix):
                      action = self._option_string_actions[option_string]
                      tup = action, option_string, explicit_arg
                      result.append(tup)
  
          # shouldn't ever get here
          else:
              self.error(_('unexpected option string: %s') % option_string)
  
          # return the collected option tuples
          return result
  
      def _get_nargs_pattern(self, action):
          # in all examples below, we have to allow for '--' args
          # which are represented as '-' in the pattern
          nargs = action.nargs
  
          # the default (None) is assumed to be a single argument
          if nargs is None:
              nargs_pattern = '(-*A-*)'
  
          # allow zero or one arguments
          elif nargs == OPTIONAL:
              nargs_pattern = '(-*A?-*)'
  
          # allow zero or more arguments
          elif nargs == ZERO_OR_MORE:
              nargs_pattern = '(-*[A-]*)'
  
          # allow one or more arguments
          elif nargs == ONE_OR_MORE:
              nargs_pattern = '(-*A[A-]*)'
  
          # allow any number of options or arguments
          elif nargs == REMAINDER:
              nargs_pattern = '([-AO]*)'
  
          # allow one argument followed by any number of options or arguments
          elif nargs == PARSER:
              nargs_pattern = '(-*A[-AO]*)'
  
          # all others should be integers
          else:
              nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs)
  
          # if this is an optional action, -- is not allowed
          if action.option_strings:
              nargs_pattern = nargs_pattern.replace('-*', '')
              nargs_pattern = nargs_pattern.replace('-', '')
  
          # return the pattern
          return nargs_pattern
  
      # ========================
      # Value conversion methods
      # ========================
      def _get_values(self, action, arg_strings):
          # for everything but PARSER, REMAINDER args, strip out first '--'
          if action.nargs not in [PARSER, REMAINDER]:
              try:
                  arg_strings.remove('--')
              except ValueError:
                  pass
  
          # optional argument produces a default when not present
          if not arg_strings and action.nargs == OPTIONAL:
              if action.option_strings:
                  value = action.const
              else:
                  value = action.default
              if isinstance(value, str):
                  value = self._get_value(action, value)
                  self._check_value(action, value)
  
          # when nargs='*' on a positional, if there were no command-line
          # args, use the default if it is anything other than None
          elif (not arg_strings and action.nargs == ZERO_OR_MORE and
                not action.option_strings):
              if action.default is not None:
                  value = action.default
              else:
                  value = arg_strings
              self._check_value(action, value)
  
          # single argument or optional argument produces a single value
          elif len(arg_strings) == 1 and action.nargs in [None, OPTIONAL]:
              arg_string, = arg_strings
              value = self._get_value(action, arg_string)
              self._check_value(action, value)
  
          # REMAINDER arguments convert all values, checking none
          elif action.nargs == REMAINDER:
              value = [self._get_value(action, v) for v in arg_strings]
  
          # PARSER arguments convert all values, but check only the first
          elif action.nargs == PARSER:
              value = [self._get_value(action, v) for v in arg_strings]
              self._check_value(action, value[0])
  
          # all other types of nargs produce a list
          else:
              value = [self._get_value(action, v) for v in arg_strings]
              for v in value:
                  self._check_value(action, v)
  
          # return the converted value
          return value
  
      def _get_value(self, action, arg_string):
          type_func = self._registry_get('type', action.type, action.type)
          if not callable(type_func):
              msg = _('%r is not callable')
              raise ArgumentError(action, msg % type_func)
  
          # convert the value to the appropriate type
          try:
              result = type_func(arg_string)
  
          # ArgumentTypeErrors indicate errors
          except ArgumentTypeError:
              name = getattr(action.type, '__name__', repr(action.type))
              msg = str(_sys.exc_info()[1])
              raise ArgumentError(action, msg)
  
          # TypeErrors or ValueErrors also indicate errors
          except (TypeError, ValueError):
              name = getattr(action.type, '__name__', repr(action.type))
              args = {'type': name, 'value': arg_string}
              msg = _('invalid %(type)s value: %(value)r')
              raise ArgumentError(action, msg % args)
  
          # return the converted value
          return result
  
      def _check_value(self, action, value):
          # converted value must be one of the choices (if specified)
          if action.choices is not None and value not in action.choices:
              args = {'value': value,
                      'choices': ', '.join(map(repr, action.choices))}
              msg = _('invalid choice: %(value)r (choose from %(choices)s)')
              raise ArgumentError(action, msg % args)
  
      # =======================
      # Help-formatting methods
      # =======================
      def format_usage(self):
          formatter = self._get_formatter()
          formatter.add_usage(self.usage, self._actions,
                              self._mutually_exclusive_groups)
          return formatter.format_help()
  
      def format_help(self):
          formatter = self._get_formatter()
  
          # usage
          formatter.add_usage(self.usage, self._actions,
                              self._mutually_exclusive_groups)
  
          # description
          formatter.add_text(self.description)
  
          # positionals, optionals and user-defined groups
          for action_group in self._action_groups:
              formatter.start_section(action_group.title)
              formatter.add_text(action_group.description)
              formatter.add_arguments(action_group._group_actions)
              formatter.end_section()
  
          # epilog
          formatter.add_text(self.epilog)
  
          # determine help from format above
          return formatter.format_help()
  
      def _get_formatter(self):
          return self.formatter_class(prog=self.prog)
  
      # =====================
      # Help-printing methods
      # =====================
      def print_usage(self, file=None):
          if file is None:
              file = _sys.stdout
          self._print_message(self.format_usage(), file)
  
      def print_help(self, file=None):
          if file is None:
              file = _sys.stdout
          self._print_message(self.format_help(), file)
  
      def _print_message(self, message, file=None):
          if message:
              if file is None:
                  file = _sys.stderr
              file.write(message)
  
      # ===============
      # Exiting methods
      # ===============
      def exit(self, status=0, message=None):
          if message:
              self._print_message(message, _sys.stderr)
          _sys.exit(status)
  
      def error(self, message):
          """error(message: string)
  
          Prints a usage message incorporating the message to stderr and
          exits.
  
          If you override this in a subclass, it should not return -- it
          should either exit or raise an exception.
          """
          self.print_usage(_sys.stderr)
          args = {'prog': self.prog, 'message': message}
          self.exit(2, _('%(prog)s: error: %(message)s\n') % args)
  
  