text: # -*- coding: iso-8859-1 -*-
  """Get useful information from live Python objects.
  
  This module encapsulates the interface provided by the internal special
  attributes (func_*, co_*, im_*, tb_*, etc.) in a friendlier fashion.
  It also provides some help for examining source code and class layout.
  
  Here are some of the useful functions provided by this module:
  
      ismodule(), isclass(), ismethod(), isfunction(), isgeneratorfunction(),
          isgenerator(), istraceback(), isframe(), iscode(), isbuiltin(),
          isroutine() - check object types
      getmembers() - get members of an object that satisfy a given condition
  
      getfile(), getsourcefile(), getsource() - find an object's source code
      getdoc(), getcomments() - get documentation on an object
      getmodule() - determine the module that an object came from
      getclasstree() - arrange classes so as to represent their hierarchy
  
      getargspec(), getargvalues() - get info about function arguments
      formatargspec(), formatargvalues() - format an argument spec
      getouterframes(), getinnerframes() - get info about frames
      currentframe() - get the current stack frame
      stack(), trace() - get info about frames on the stack or in a traceback
  """
  
  # This module is in the public domain.  No warranties.
  
  __author__ = 'Ka-Ping Yee <ping@lfw.org>'
  __date__ = '1 Jan 2001'
  
  import sys
  import os
  import types
  import string
  import re
  import dis
  import imp
  import tokenize
  import linecache
  from operator import attrgetter
  from collections import namedtuple
  
  # These constants are from Include/code.h.
  CO_OPTIMIZED, CO_NEWLOCALS, CO_VARARGS, CO_VARKEYWORDS = 0x1, 0x2, 0x4, 0x8
  CO_NESTED, CO_GENERATOR, CO_NOFREE = 0x10, 0x20, 0x40
  # See Include/object.h
  TPFLAGS_IS_ABSTRACT = 1 << 20
  
  # ----------------------------------------------------------- type-checking
  def ismodule(object):
      """Return true if the object is a module.
  
      Module objects provide these attributes:
          __doc__         documentation string
          __file__        filename (missing for built-in modules)"""
      return isinstance(object, types.ModuleType)
  
  def isclass(object):
      """Return true if the object is a class.
  
      Class objects provide these attributes:
          __doc__         documentation string
          __module__      name of module in which this class was defined"""
      return isinstance(object, types.ClassType) or hasattr(object, '__bases__')
  
  def ismethod(object):
      """Return true if the object is an instance method.
  
      Instance method objects provide these attributes:
          __doc__         documentation string
          __name__        name with which this method was defined
          im_class        class object in which this method belongs
          im_func         function object containing implementation of method
          im_self         instance to which this method is bound, or None"""
      return isinstance(object, types.MethodType)
  
  def ismethoddescriptor(object):
      """Return true if the object is a method descriptor.
  
      But not if ismethod() or isclass() or isfunction() are true.
  
      This is new in Python 2.2, and, for example, is true of int.__add__.
      An object passing this test has a __get__ attribute but not a __set__
      attribute, but beyond that the set of attributes varies.  __name__ is
      usually sensible, and __doc__ often is.
  
      Methods implemented via descriptors that also pass one of the other
      tests return false from the ismethoddescriptor() test, simply because
      the other tests promise more -- you can, e.g., count on having the
      im_func attribute (etc) when an object passes ismethod()."""
      return (hasattr(object, "__get__")
              and not hasattr(object, "__set__") # else it's a data descriptor
              and not ismethod(object)           # mutual exclusion
              and not isfunction(object)
              and not isclass(object))
  
  def isdatadescriptor(object):
      """Return true if the object is a data descriptor.
  
      Data descriptors have both a __get__ and a __set__ attribute.  Examples are
      properties (defined in Python) and getsets and members (defined in C).
      Typically, data descriptors will also have __name__ and __doc__ attributes
      (properties, getsets, and members have both of these attributes), but this
      is not guaranteed."""
      return (hasattr(object, "__set__") and hasattr(object, "__get__"))
  
  if hasattr(types, 'MemberDescriptorType'):
      # CPython and equivalent
      def ismemberdescriptor(object):
          """Return true if the object is a member descriptor.
  
          Member descriptors are specialized descriptors defined in extension
          modules."""
          return isinstance(object, types.MemberDescriptorType)
  else:
      # Other implementations
      def ismemberdescriptor(object):
          """Return true if the object is a member descriptor.
  
          Member descriptors are specialized descriptors defined in extension
          modules."""
          return False
  
  if hasattr(types, 'GetSetDescriptorType'):
      # CPython and equivalent
      def isgetsetdescriptor(object):
          """Return true if the object is a getset descriptor.
  
          getset descriptors are specialized descriptors defined in extension
          modules."""
          return isinstance(object, types.GetSetDescriptorType)
  else:
      # Other implementations
      def isgetsetdescriptor(object):
          """Return true if the object is a getset descriptor.
  
          getset descriptors are specialized descriptors defined in extension
          modules."""
          return False
  
  def isfunction(object):
      """Return true if the object is a user-defined function.
  
      Function objects provide these attributes:
          __doc__         documentation string
          __name__        name with which this function was defined
          func_code       code object containing compiled function bytecode
          func_defaults   tuple of any default values for arguments
          func_doc        (same as __doc__)
          func_globals    global namespace in which this function was defined
          func_name       (same as __name__)"""
      return isinstance(object, types.FunctionType)
  
  def isgeneratorfunction(object):
      """Return true if the object is a user-defined generator function.
  
      Generator function objects provides same attributes as functions.
  
      See isfunction.__doc__ for attributes listing."""
      return bool((isfunction(object) or ismethod(object)) and
                  object.func_code.co_flags & CO_GENERATOR)
  
  def isgenerator(object):
      """Return true if the object is a generator.
  
      Generator objects provide these attributes:
          __iter__        defined to support interation over container
          close           raises a new GeneratorExit exception inside the
                          generator to terminate the iteration
          gi_code         code object
          gi_frame        frame object or possibly None once the generator has
                          been exhausted
          gi_running      set to 1 when generator is executing, 0 otherwise
          next            return the next item from the container
          send            resumes the generator and "sends" a value that becomes
                          the result of the current yield-expression
          throw           used to raise an exception inside the generator"""
      return isinstance(object, types.GeneratorType)
  
  def istraceback(object):
      """Return true if the object is a traceback.
  
      Traceback objects provide these attributes:
          tb_frame        frame object at this level
          tb_lasti        index of last attempted instruction in bytecode
          tb_lineno       current line number in Python source code
          tb_next         next inner traceback object (called by this level)"""
      return isinstance(object, types.TracebackType)
  
  def isframe(object):
      """Return true if the object is a frame object.
  
      Frame objects provide these attributes:
          f_back          next outer frame object (this frame's caller)
          f_builtins      built-in namespace seen by this frame
          f_code          code object being executed in this frame
          f_exc_traceback traceback if raised in this frame, or None
          f_exc_type      exception type if raised in this frame, or None
          f_exc_value     exception value if raised in this frame, or None
          f_globals       global namespace seen by this frame
          f_lasti         index of last attempted instruction in bytecode
          f_lineno        current line number in Python source code
          f_locals        local namespace seen by this frame
          f_restricted    0 or 1 if frame is in restricted execution mode
          f_trace         tracing function for this frame, or None"""
      return isinstance(object, types.FrameType)
  
  def iscode(object):
      """Return true if the object is a code object.
  
      Code objects provide these attributes:
          co_argcount     number of arguments (not including * or ** args)
          co_code         string of raw compiled bytecode
          co_consts       tuple of constants used in the bytecode
          co_filename     name of file in which this code object was created
          co_firstlineno  number of first line in Python source code
          co_flags        bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg
          co_lnotab       encoded mapping of line numbers to bytecode indices
          co_name         name with which this code object was defined
          co_names        tuple of names of local variables
          co_nlocals      number of local variables
          co_stacksize    virtual machine stack space required
          co_varnames     tuple of names of arguments and local variables"""
      return isinstance(object, types.CodeType)
  
  def isbuiltin(object):
      """Return true if the object is a built-in function or method.
  
      Built-in functions and methods provide these attributes:
          __doc__         documentation string
          __name__        original name of this function or method
          __self__        instance to which a method is bound, or None"""
      return isinstance(object, types.BuiltinFunctionType)
  
  def isroutine(object):
      """Return true if the object is any kind of function or method."""
      return (isbuiltin(object)
              or isfunction(object)
              or ismethod(object)
              or ismethoddescriptor(object))
  
  def isabstract(object):
      """Return true if the object is an abstract base class (ABC)."""
      return isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT
  
  def getmembers(object, predicate=None):
      """Return all members of an object as (name, value) pairs sorted by name.
      Optionally, only return members that satisfy a given predicate."""
      results = []
      for key in dir(object):
          value = getattr(object, key)
          if not predicate or predicate(value):
              results.append((key, value))
      results.sort()
      return results
  
  Attribute = namedtuple('Attribute', 'name kind defining_class object')
  
  def classify_class_attrs(cls):
      """Return list of attribute-descriptor tuples.
  
      For each name in dir(cls), the return list contains a 4-tuple
      with these elements:
  
          0. The name (a string).
  
          1. The kind of attribute this is, one of these strings:
                 'class method'    created via classmethod()
                 'static method'   created via staticmethod()
                 'property'        created via property()
                 'method'          any other flavor of method
                 'data'            not a method
  
          2. The class which defined this attribute (a class).
  
          3. The object as obtained directly from the defining class's
             __dict__, not via getattr.  This is especially important for
             data attributes:  C.data is just a data object, but
             C.__dict__['data'] may be a data descriptor with additional
             info, like a __doc__ string.
      """
  
      mro = getmro(cls)
      names = dir(cls)
      result = []
      for name in names:
          # Get the object associated with the name.
          # Getting an obj from the __dict__ sometimes reveals more than
          # using getattr.  Static and class methods are dramatic examples.
          if name in cls.__dict__:
              obj = cls.__dict__[name]
          else:
              obj = getattr(cls, name)
  
          # Figure out where it was defined.
          homecls = getattr(obj, "__objclass__", None)
          if homecls is None:
              # search the dicts.
              for base in mro:
                  if name in base.__dict__:
                      homecls = base
                      break
  
          # Get the object again, in order to get it from the defining
          # __dict__ instead of via getattr (if possible).
          if homecls is not None and name in homecls.__dict__:
              obj = homecls.__dict__[name]
  
          # Also get the object via getattr.
          obj_via_getattr = getattr(cls, name)
  
          # Classify the object.
          if isinstance(obj, staticmethod):
              kind = "static method"
          elif isinstance(obj, classmethod):
              kind = "class method"
          elif isinstance(obj, property):
              kind = "property"
          elif (ismethod(obj_via_getattr) or
                ismethoddescriptor(obj_via_getattr)):
              kind = "method"
          else:
              kind = "data"
  
          result.append(Attribute(name, kind, homecls, obj))
  
      return result
  
  # ----------------------------------------------------------- class helpers
  def _searchbases(cls, accum):
      # Simulate the "classic class" search order.
      if cls in accum:
          return
      accum.append(cls)
      for base in cls.__bases__:
          _searchbases(base, accum)
  
  def getmro(cls):
      "Return tuple of base classes (including cls) in method resolution order."
      if hasattr(cls, "__mro__"):
          return cls.__mro__
      else:
          result = []
          _searchbases(cls, result)
          return tuple(result)
  
  # -------------------------------------------------- source code extraction
  def indentsize(line):
      """Return the indent size, in spaces, at the start of a line of text."""
      expline = string.expandtabs(line)
      return len(expline) - len(string.lstrip(expline))
  
  def getdoc(object):
      """Get the documentation string for an object.
  
      All tabs are expanded to spaces.  To clean up docstrings that are
      indented to line up with blocks of code, any whitespace than can be
      uniformly removed from the second line onwards is removed."""
      try:
          doc = object.__doc__
      except AttributeError:
          return None
      if not isinstance(doc, types.StringTypes):
          return None
      return cleandoc(doc)
  
  def cleandoc(doc):
      """Clean up indentation from docstrings.
  
      Any whitespace that can be uniformly removed from the second line
      onwards is removed."""
      try:
          lines = string.split(string.expandtabs(doc), '\n')
      except UnicodeError:
          return None
      else:
          # Find minimum indentation of any non-blank lines after first line.
          margin = sys.maxint
          for line in lines[1:]:
              content = len(string.lstrip(line))
              if content:
                  indent = len(line) - content
                  margin = min(margin, indent)
          # Remove indentation.
          if lines:
              lines[0] = lines[0].lstrip()
          if margin < sys.maxint:
              for i in range(1, len(lines)): lines[i] = lines[i][margin:]
          # Remove any trailing or leading blank lines.
          while lines and not lines[-1]:
              lines.pop()
          while lines and not lines[0]:
              lines.pop(0)
          return string.join(lines, '\n')
  
  def getfile(object):
      """Work out which source or compiled file an object was defined in."""
      if ismodule(object):
          if hasattr(object, '__file__'):
              return object.__file__
          raise TypeError('arg is a built-in module')
      if isclass(object):
          object = sys.modules.get(object.__module__)
          if hasattr(object, '__file__'):
              return object.__file__
          raise TypeError('arg is a built-in class')
      if ismethod(object):
          object = object.im_func
      if isfunction(object):
          object = object.func_code
      if istraceback(object):
          object = object.tb_frame
      if isframe(object):
          object = object.f_code
      if iscode(object):
          return object.co_filename
      raise TypeError('arg is not a module, class, method, '
                      'function, traceback, frame, or code object')
  
  ModuleInfo = namedtuple('ModuleInfo', 'name suffix mode module_type')
  
  def getmoduleinfo(path):
      """Get the module name, suffix, mode, and module type for a given file."""
      filename = os.path.basename(path)
      suffixes = map(lambda info:
                     (-len(info[0]), info[0], info[1], info[2]),
                      imp.get_suffixes())
      suffixes.sort() # try longest suffixes first, in case they overlap
      for neglen, suffix, mode, mtype in suffixes:
          if filename[neglen:] == suffix:
              return ModuleInfo(filename[:neglen], suffix, mode, mtype)
  
  def getmodulename(path):
      """Return the module name for a given file, or None."""
      info = getmoduleinfo(path)
      if info: return info[0]
  
  def getsourcefile(object):
      """Return the Python source file an object was defined in, if it exists."""
      filename = getfile(object)
      if string.lower(filename[-4:]) in ('.pyc', '.pyo'):
          filename = filename[:-4] + '.py'
      for suffix, mode, kind in imp.get_suffixes():
          if 'b' in mode and string.lower(filename[-len(suffix):]) == suffix:
              # Looks like a binary file.  We want to only return a text file.
              return None
      if os.path.exists(filename):
          return filename
      # only return a non-existent filename if the module has a PEP 302 loader
      if hasattr(getmodule(object, filename), '__loader__'):
          return filename
  
  def getabsfile(object, _filename=None):
      """Return an absolute path to the source or compiled file for an object.
  
      The idea is for each object to have a unique origin, so this routine
      normalizes the result as much as possible."""
      if _filename is None:
          _filename = getsourcefile(object) or getfile(object)
      return os.path.normcase(os.path.abspath(_filename))
  
  modulesbyfile = {}
  _filesbymodname = {}
  
  def getmodule(object, _filename=None):
      """Return the module an object was defined in, or None if not found."""
      if ismodule(object):
          return object
      if hasattr(object, '__module__'):
          return sys.modules.get(object.__module__)
      # Try the filename to modulename cache
      if _filename is not None and _filename in modulesbyfile:
          return sys.modules.get(modulesbyfile[_filename])
      # Try the cache again with the absolute file name
      try:
          file = getabsfile(object, _filename)
      except TypeError:
          return None
      if file in modulesbyfile:
          return sys.modules.get(modulesbyfile[file])
      # Update the filename to module name cache and check yet again
      # Copy sys.modules in order to cope with changes while iterating
      for modname, module in sys.modules.items():
          if ismodule(module) and hasattr(module, '__file__'):
              f = module.__file__
              if f == _filesbymodname.get(modname, None):
                  # Have already mapped this module, so skip it
                  continue
              _filesbymodname[modname] = f
              f = getabsfile(module)
              # Always map to the name the module knows itself by
              modulesbyfile[f] = modulesbyfile[
                  os.path.realpath(f)] = module.__name__
      if file in modulesbyfile:
          return sys.modules.get(modulesbyfile[file])
      # Check the main module
      main = sys.modules['__main__']
      if not hasattr(object, '__name__'):
          return None
      if hasattr(main, object.__name__):
          mainobject = getattr(main, object.__name__)
          if mainobject is object:
              return main
      # Check builtins
      builtin = sys.modules['__builtin__']
      if hasattr(builtin, object.__name__):
          builtinobject = getattr(builtin, object.__name__)
          if builtinobject is object:
              return builtin
  
  def findsource(object):
      """Return the entire source file and starting line number for an object.
  
      The argument may be a module, class, method, function, traceback, frame,
      or code object.  The source code is returned as a list of all the lines
      in the file and the line number indexes a line in that list.  An IOError
      is raised if the source code cannot be retrieved."""
      file = getsourcefile(object) or getfile(object)
      module = getmodule(object, file)
      if module:
          lines = linecache.getlines(file, module.__dict__)
      else:
          lines = linecache.getlines(file)
      if not lines:
          raise IOError('could not get source code')
  
      if ismodule(object):
          return lines, 0
  
      if isclass(object):
          name = object.__name__
          pat = re.compile(r'^(\s*)class\s*' + name + r'\b')
          # make some effort to find the best matching class definition:
          # use the one with the least indentation, which is the one
          # that's most probably not inside a function definition.
          candidates = []
          for i in range(len(lines)):
              match = pat.match(lines[i])
              if match:
                  # if it's at toplevel, it's already the best one
                  if lines[i][0] == 'c':
                      return lines, i
                  # else add whitespace to candidate list
                  candidates.append((match.group(1), i))
          if candidates:
              # this will sort by whitespace, and by line number,
              # less whitespace first
              candidates.sort()
              return lines, candidates[0][1]
          else:
              raise IOError('could not find class definition')
  
      if ismethod(object):
          object = object.im_func
      if isfunction(object):
          object = object.func_code
      if istraceback(object):
          object = object.tb_frame
      if isframe(object):
          object = object.f_code
      if iscode(object):
          if not hasattr(object, 'co_firstlineno'):
              raise IOError('could not find function definition')
          lnum = object.co_firstlineno - 1
          pat = re.compile(r'^(\s*def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
          while lnum > 0:
              if pat.match(lines[lnum]): break
              lnum = lnum - 1
          return lines, lnum
      raise IOError('could not find code object')
  
  def getcomments(object):
      """Get lines of comments immediately preceding an object's source code.
  
      Returns None when source can't be found.
      """
      try:
          lines, lnum = findsource(object)
      except (IOError, TypeError):
          return None
  
      if ismodule(object):
          # Look for a comment block at the top of the file.
          start = 0
          if lines and lines[0][:2] == '#!': start = 1
          while start < len(lines) and string.strip(lines[start]) in ('', '#'):
              start = start + 1
          if start < len(lines) and lines[start][:1] == '#':
              comments = []
              end = start
              while end < len(lines) and lines[end][:1] == '#':
                  comments.append(string.expandtabs(lines[end]))
                  end = end + 1
              return string.join(comments, '')
  
      # Look for a preceding block of comments at the same indentation.
      elif lnum > 0:
          indent = indentsize(lines[lnum])
          end = lnum - 1
          if end >= 0 and string.lstrip(lines[end])[:1] == '#' and \
              indentsize(lines[end]) == indent:
              comments = [string.lstrip(string.expandtabs(lines[end]))]
              if end > 0:
                  end = end - 1
                  comment = string.lstrip(string.expandtabs(lines[end]))
                  while comment[:1] == '#' and indentsize(lines[end]) == indent:
                      comments[:0] = [comment]
                      end = end - 1
                      if end < 0: break
                      comment = string.lstrip(string.expandtabs(lines[end]))
              while comments and string.strip(comments[0]) == '#':
                  comments[:1] = []
              while comments and string.strip(comments[-1]) == '#':
                  comments[-1:] = []
              return string.join(comments, '')
  
  class EndOfBlock(Exception): pass
  
  class BlockFinder:
      """Provide a tokeneater() method to detect the end of a code block."""
      def __init__(self):
          self.indent = 0
          self.islambda = False
          self.started = False
          self.passline = False
          self.last = 1
  
      def tokeneater(self, type, token, srow_scol, erow_ecol, line):
          srow, scol = srow_scol
          erow, ecol = erow_ecol
          if not self.started:
              # look for the first "def", "class" or "lambda"
              if token in ("def", "class", "lambda"):
                  if token == "lambda":
                      self.islambda = True
                  self.started = True
              self.passline = True    # skip to the end of the line
          elif type == tokenize.NEWLINE:
              self.passline = False   # stop skipping when a NEWLINE is seen
              self.last = srow
              if self.islambda:       # lambdas always end at the first NEWLINE
                  raise EndOfBlock
          elif self.passline:
              pass
          elif type == tokenize.INDENT:
              self.indent = self.indent + 1
              self.passline = True
          elif type == tokenize.DEDENT:
              self.indent = self.indent - 1
              # the end of matching indent/dedent pairs end a block
              # (note that this only works for "def"/"class" blocks,
              #  not e.g. for "if: else:" or "try: finally:" blocks)
              if self.indent <= 0:
                  raise EndOfBlock
          elif self.indent == 0 and type not in (tokenize.COMMENT, tokenize.NL):
              # any other token on the same indentation level end the previous
              # block as well, except the pseudo-tokens COMMENT and NL.
              raise EndOfBlock
  
  def getblock(lines):
      """Extract the block of code at the top of the given list of lines."""
      blockfinder = BlockFinder()
      try:
          tokenize.tokenize(iter(lines).next, blockfinder.tokeneater)
      except (EndOfBlock, IndentationError):
          pass
      return lines[:blockfinder.last]
  
  def getsourcelines(object):
      """Return a list of source lines and starting line number for an object.
  
      The argument may be a module, class, method, function, traceback, frame,
      or code object.  The source code is returned as a list of the lines
      corresponding to the object and the line number indicates where in the
      original source file the first line of code was found.  An IOError is
      raised if the source code cannot be retrieved."""
      lines, lnum = findsource(object)
  
      if ismodule(object): return lines, 0
      else: return getblock(lines[lnum:]), lnum + 1
  
  def getsource(object):
      """Return the text of the source code for an object.
  
      The argument may be a module, class, method, function, traceback, frame,
      or code object.  The source code is returned as a single string.  An
      IOError is raised if the source code cannot be retrieved."""
      lines, lnum = getsourcelines(object)
      return string.join(lines, '')
  
  # --------------------------------------------------- class tree extraction
  def walktree(classes, children, parent):
      """Recursive helper function for getclasstree()."""
      results = []
      classes.sort(key=attrgetter('__module__', '__name__'))
      for c in classes:
          results.append((c, c.__bases__))
          if c in children:
              results.append(walktree(children[c], children, c))
      return results
  
  def getclasstree(classes, unique=0):
      """Arrange the given list of classes into a hierarchy of nested lists.
  
      Where a nested list appears, it contains classes derived from the class
      whose entry immediately precedes the list.  Each entry is a 2-tuple
      containing a class and a tuple of its base classes.  If the 'unique'
      argument is true, exactly one entry appears in the returned structure
      for each class in the given list.  Otherwise, classes using multiple
      inheritance and their descendants will appear multiple times."""
      children = {}
      roots = []
      for c in classes:
          if c.__bases__:
              for parent in c.__bases__:
                  if not parent in children:
                      children[parent] = []
                  children[parent].append(c)
                  if unique and parent in classes: break
          elif c not in roots:
              roots.append(c)
      for parent in children:
          if parent not in classes:
              roots.append(parent)
      return walktree(roots, children, None)
  
  # ------------------------------------------------ argument list extraction
  Arguments = namedtuple('Arguments', 'args varargs keywords')
  
  def getargs(co):
      """Get information about the arguments accepted by a code object.
  
      Three things are returned: (args, varargs, varkw), where 'args' is
      a list of argument names (possibly containing nested lists), and
      'varargs' and 'varkw' are the names of the * and ** arguments or None."""
  
      if not iscode(co):
          raise TypeError('arg is not a code object')
  
      nargs = co.co_argcount
      names = co.co_varnames
      args = list(names[:nargs])
      step = 0
  
      # The following acrobatics are for anonymous (tuple) arguments.
      for i in range(nargs):
          if args[i][:1] in ('', '.'):
              stack, remain, count = [], [], []
              while step < len(co.co_code):
                  op = ord(co.co_code[step])
                  step = step + 1
                  if op >= dis.HAVE_ARGUMENT:
                      opname = dis.opname[op]
                      value = ord(co.co_code[step]) + ord(co.co_code[step+1])*256
                      step = step + 2
                      if opname in ('UNPACK_TUPLE', 'UNPACK_SEQUENCE'):
                          remain.append(value)
                          count.append(value)
                      elif opname == 'STORE_FAST':
                          stack.append(names[value])
  
                          # Special case for sublists of length 1: def foo((bar))
                          # doesn't generate the UNPACK_TUPLE bytecode, so if
                          # `remain` is empty here, we have such a sublist.
                          if not remain:
                              stack[0] = [stack[0]]
                              break
                          else:
                              remain[-1] = remain[-1] - 1
                              while remain[-1] == 0:
                                  remain.pop()
                                  size = count.pop()
                                  stack[-size:] = [stack[-size:]]
                                  if not remain: break
                                  remain[-1] = remain[-1] - 1
                              if not remain: break
              args[i] = stack[0]
  
      varargs = None
      if co.co_flags & CO_VARARGS:
          varargs = co.co_varnames[nargs]
          nargs = nargs + 1
      varkw = None
      if co.co_flags & CO_VARKEYWORDS:
          varkw = co.co_varnames[nargs]
      return Arguments(args, varargs, varkw)
  
  ArgSpec = namedtuple('ArgSpec', 'args varargs keywords defaults')
  
  def getargspec(func):
      """Get the names and default values of a function's arguments.
  
      A tuple of four things is returned: (args, varargs, varkw, defaults).
      'args' is a list of the argument names (it may contain nested lists).
      'varargs' and 'varkw' are the names of the * and ** arguments or None.
      'defaults' is an n-tuple of the default values of the last n arguments.
      """
  
      if ismethod(func):
          func = func.im_func
      if not isfunction(func):
          raise TypeError('arg is not a Python function')
      args, varargs, varkw = getargs(func.func_code)
      return ArgSpec(args, varargs, varkw, func.func_defaults)
  
  ArgInfo = namedtuple('ArgInfo', 'args varargs keywords locals')
  
  def getargvalues(frame):
      """Get information about arguments passed into a particular frame.
  
      A tuple of four things is returned: (args, varargs, varkw, locals).
      'args' is a list of the argument names (it may contain nested lists).
      'varargs' and 'varkw' are the names of the * and ** arguments or None.
      'locals' is the locals dictionary of the given frame."""
      args, varargs, varkw = getargs(frame.f_code)
      return ArgInfo(args, varargs, varkw, frame.f_locals)
  
  def joinseq(seq):
      if len(seq) == 1:
          return '(' + seq[0] + ',)'
      else:
          return '(' + string.join(seq, ', ') + ')'
  
  def strseq(object, convert, join=joinseq):
      """Recursively walk a sequence, stringifying each element."""
      if type(object) in (list, tuple):
          return join(map(lambda o, c=convert, j=join: strseq(o, c, j), object))
      else:
          return convert(object)
  
  def formatargspec(args, varargs=None, varkw=None, defaults=None,
                    formatarg=str,
                    formatvarargs=lambda name: '*' + name,
                    formatvarkw=lambda name: '**' + name,
                    formatvalue=lambda value: '=' + repr(value),
                    join=joinseq):
      """Format an argument spec from the 4 values returned by getargspec.
  
      The first four arguments are (args, varargs, varkw, defaults).  The
      other four arguments are the corresponding optional formatting functions
      that are called to turn names and values into strings.  The ninth
      argument is an optional function to format the sequence of arguments."""
      specs = []
      if defaults:
          firstdefault = len(args) - len(defaults)
      for i in range(len(args)):
          spec = strseq(args[i], formatarg, join)
          if defaults and i >= firstdefault:
              spec = spec + formatvalue(defaults[i - firstdefault])
          specs.append(spec)
      if varargs is not None:
          specs.append(formatvarargs(varargs))
      if varkw is not None:
          specs.append(formatvarkw(varkw))
      return '(' + string.join(specs, ', ') + ')'
  
  def formatargvalues(args, varargs, varkw, locals,
                      formatarg=str,
                      formatvarargs=lambda name: '*' + name,
                      formatvarkw=lambda name: '**' + name,
                      formatvalue=lambda value: '=' + repr(value),
                      join=joinseq):
      """Format an argument spec from the 4 values returned by getargvalues.
  
      The first four arguments are (args, varargs, varkw, locals).  The
      next four arguments are the corresponding optional formatting functions
      that are called to turn names and values into strings.  The ninth
      argument is an optional function to format the sequence of arguments."""
      def convert(name, locals=locals,
                  formatarg=formatarg, formatvalue=formatvalue):
          return formatarg(name) + formatvalue(locals[name])
      specs = []
      for i in range(len(args)):
          specs.append(strseq(args[i], convert, join))
      if varargs:
          specs.append(formatvarargs(varargs) + formatvalue(locals[varargs]))
      if varkw:
          specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
      return '(' + string.join(specs, ', ') + ')'
  
  # -------------------------------------------------- stack frame extraction
  
  Traceback = namedtuple('Traceback', 'filename lineno function code_context index')
  
  def getframeinfo(frame, context=1):
      """Get information about a frame or traceback object.
  
      A tuple of five things is returned: the filename, the line number of
      the current line, the function name, a list of lines of context from
      the source code, and the index of the current line within that list.
      The optional second argument specifies the number of lines of context
      to return, which are centered around the current line."""
      if istraceback(frame):
          lineno = frame.tb_lineno
          frame = frame.tb_frame
      else:
          lineno = frame.f_lineno
      if not isframe(frame):
          raise TypeError('arg is not a frame or traceback object')
  
      filename = getsourcefile(frame) or getfile(frame)
      if context > 0:
          start = lineno - 1 - context//2
          try:
              lines, lnum = findsource(frame)
          except IOError:
              lines = index = None
          else:
              start = max(start, 1)
              start = max(0, min(start, len(lines) - context))
              lines = lines[start:start+context]
              index = lineno - 1 - start
      else:
          lines = index = None
  
      return Traceback(filename, lineno, frame.f_code.co_name, lines, index)
  
  def getlineno(frame):
      """Get the line number from a frame object, allowing for optimization."""
      # FrameType.f_lineno is now a descriptor that grovels co_lnotab
      return frame.f_lineno
  
  def getouterframes(frame, context=1):
      """Get a list of records for a frame and all higher (calling) frames.
  
      Each record contains a frame object, filename, line number, function
      name, a list of lines of context, and index within the context."""
      framelist = []
      while frame:
          framelist.append((frame,) + getframeinfo(frame, context))
          frame = frame.f_back
      return framelist
  
  def getinnerframes(tb, context=1):
      """Get a list of records for a traceback's frame and all lower frames.
  
      Each record contains a frame object, filename, line number, function
      name, a list of lines of context, and index within the context."""
      framelist = []
      while tb:
          framelist.append((tb.tb_frame,) + getframeinfo(tb, context))
          tb = tb.tb_next
      return framelist
  
  if hasattr(sys, '_getframe'):
      currentframe = sys._getframe
  else:
      currentframe = lambda _=None: None
  
  def stack(context=1):
      """Return a list of records for the stack above the caller's frame."""
      return getouterframes(sys._getframe(1), context)
  
  def trace(context=1):
      """Return a list of records for the stack below the current exception."""
      return getinnerframes(sys.exc_info()[2], context)
  