text: """Text wrapping and filling.
  """
  
  # Copyright (C) 1999-2001 Gregory P. Ward.
  # Copyright (C) 2002, 2003 Python Software Foundation.
  # Written by Greg Ward <gward@python.net>
  
  import re
  
  __all__ = ['TextWrapper', 'wrap', 'fill', 'dedent', 'indent', 'shorten']
  
  # Hardcode the recognized whitespace characters to the US-ASCII
  # whitespace characters.  The main reason for doing this is that in
  # ISO-8859-1, 0xa0 is non-breaking whitespace, so in certain locales
  # that character winds up in string.whitespace.  Respecting
  # string.whitespace in those cases would 1) make textwrap treat 0xa0 the
  # same as any other whitespace char, which is clearly wrong (it's a
  # *non-breaking* space), 2) possibly cause problems with Unicode,
  # since 0xa0 is not in range(128).
  _whitespace = '\t\n\x0b\x0c\r '
  
  class TextWrapper:
      """
      Object for wrapping/filling text.  The public interface consists of
      the wrap() and fill() methods; the other methods are just there for
      subclasses to override in order to tweak the default behaviour.
      If you want to completely replace the main wrapping algorithm,
      you'll probably have to override _wrap_chunks().
  
      Several instance attributes control various aspects of wrapping:
        width (default: 70)
          the maximum width of wrapped lines (unless break_long_words
          is false)
        initial_indent (default: "")
          string that will be prepended to the first line of wrapped
          output.  Counts towards the line's width.
        subsequent_indent (default: "")
          string that will be prepended to all lines save the first
          of wrapped output; also counts towards each line's width.
        expand_tabs (default: true)
          Expand tabs in input text to spaces before further processing.
          Each tab will become 0 .. 'tabsize' spaces, depending on its position
          in its line.  If false, each tab is treated as a single character.
        tabsize (default: 8)
          Expand tabs in input text to 0 .. 'tabsize' spaces, unless
          'expand_tabs' is false.
        replace_whitespace (default: true)
          Replace all whitespace characters in the input text by spaces
          after tab expansion.  Note that if expand_tabs is false and
          replace_whitespace is true, every tab will be converted to a
          single space!
        fix_sentence_endings (default: false)
          Ensure that sentence-ending punctuation is always followed
          by two spaces.  Off by default because the algorithm is
          (unavoidably) imperfect.
        break_long_words (default: true)
          Break words longer than 'width'.  If false, those words will not
          be broken, and some lines might be longer than 'width'.
        break_on_hyphens (default: true)
          Allow breaking hyphenated words. If true, wrapping will occur
          preferably on whitespaces and right after hyphens part of
          compound words.
        drop_whitespace (default: true)
          Drop leading and trailing whitespace from lines.
        max_lines (default: None)
          Truncate wrapped lines.
        placeholder (default: ' [...]')
          Append to the last line of truncated text.
      """
  
      unicode_whitespace_trans = {}
      uspace = ord(' ')
      for x in _whitespace:
          unicode_whitespace_trans[ord(x)] = uspace
  
      # This funky little regex is just the trick for splitting
      # text up into word-wrappable chunks.  E.g.
      #   "Hello there -- you goof-ball, use the -b option!"
      # splits into
      #   Hello/ /there/ /--/ /you/ /goof-/ball,/ /use/ /the/ /-b/ /option!
      # (after stripping out empty strings).
      wordsep_re = re.compile(
          r'(\s+|'                                  # any whitespace
          r'[^\s\w]*\w+[^0-9\W]-(?=\w+[^0-9\W])|'   # hyphenated words
          r'(?<=[\w\!\"\'\&\.\,\?])-{2,}(?=\w))')   # em-dash
  
      # This less funky little regex just split on recognized spaces. E.g.
      #   "Hello there -- you goof-ball, use the -b option!"
      # splits into
      #   Hello/ /there/ /--/ /you/ /goof-ball,/ /use/ /the/ /-b/ /option!/
      wordsep_simple_re = re.compile(r'(\s+)')
  
      # XXX this is not locale- or charset-aware -- string.lowercase
      # is US-ASCII only (and therefore English-only)
      sentence_end_re = re.compile(r'[a-z]'             # lowercase letter
                                   r'[\.\!\?]'          # sentence-ending punct.
                                   r'[\"\']?'           # optional end-of-quote
                                   r'\Z')               # end of chunk
  
  
      def __init__(self,
                   width=70,
                   initial_indent="",
                   subsequent_indent="",
                   expand_tabs=True,
                   replace_whitespace=True,
                   fix_sentence_endings=False,
                   break_long_words=True,
                   drop_whitespace=True,
                   break_on_hyphens=True,
                   tabsize=8,
                   *,
                   max_lines=None,
                   placeholder=' [...]'):
          self.width = width
          self.initial_indent = initial_indent
          self.subsequent_indent = subsequent_indent
          self.expand_tabs = expand_tabs
          self.replace_whitespace = replace_whitespace
          self.fix_sentence_endings = fix_sentence_endings
          self.break_long_words = break_long_words
          self.drop_whitespace = drop_whitespace
          self.break_on_hyphens = break_on_hyphens
          self.tabsize = tabsize
          self.max_lines = max_lines
          self.placeholder = placeholder
  
  
      # -- Private methods -----------------------------------------------
      # (possibly useful for subclasses to override)
  
      def _munge_whitespace(self, text):
          """_munge_whitespace(text : string) -> string
  
          Munge whitespace in text: expand tabs and convert all other
          whitespace characters to spaces.  Eg. " foo\\tbar\\n\\nbaz"
          becomes " foo    bar  baz".
          """
          if self.expand_tabs:
              text = text.expandtabs(self.tabsize)
          if self.replace_whitespace:
              text = text.translate(self.unicode_whitespace_trans)
          return text
  
  
      def _split(self, text):
          """_split(text : string) -> [string]
  
          Split the text to wrap into indivisible chunks.  Chunks are
          not quite the same as words; see _wrap_chunks() for full
          details.  As an example, the text
            Look, goof-ball -- use the -b option!
          breaks into the following chunks:
            'Look,', ' ', 'goof-', 'ball', ' ', '--', ' ',
            'use', ' ', 'the', ' ', '-b', ' ', 'option!'
          if break_on_hyphens is True, or in:
            'Look,', ' ', 'goof-ball', ' ', '--', ' ',
            'use', ' ', 'the', ' ', '-b', ' ', option!'
          otherwise.
          """
          if self.break_on_hyphens is True:
              chunks = self.wordsep_re.split(text)
          else:
              chunks = self.wordsep_simple_re.split(text)
          chunks = [c for c in chunks if c]
          return chunks
  
      def _fix_sentence_endings(self, chunks):
          """_fix_sentence_endings(chunks : [string])
  
          Correct for sentence endings buried in 'chunks'.  Eg. when the
          original text contains "... foo.\\nBar ...", munge_whitespace()
          and split() will convert that to [..., "foo.", " ", "Bar", ...]
          which has one too few spaces; this method simply changes the one
          space to two.
          """
          i = 0
          patsearch = self.sentence_end_re.search
          while i < len(chunks)-1:
              if chunks[i+1] == " " and patsearch(chunks[i]):
                  chunks[i+1] = "  "
                  i += 2
              else:
                  i += 1
  
      def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
          """_handle_long_word(chunks : [string],
                               cur_line : [string],
                               cur_len : int, width : int)
  
          Handle a chunk of text (most likely a word, not whitespace) that
          is too long to fit in any line.
          """
          # Figure out when indent is larger than the specified width, and make
          # sure at least one character is stripped off on every pass
          if width < 1:
              space_left = 1
          else:
              space_left = width - cur_len
  
          # If we're allowed to break long words, then do so: put as much
          # of the next chunk onto the current line as will fit.
          if self.break_long_words:
              cur_line.append(reversed_chunks[-1][:space_left])
              reversed_chunks[-1] = reversed_chunks[-1][space_left:]
  
          # Otherwise, we have to preserve the long word intact.  Only add
          # it to the current line if there's nothing already there --
          # that minimizes how much we violate the width constraint.
          elif not cur_line:
              cur_line.append(reversed_chunks.pop())
  
          # If we're not allowed to break long words, and there's already
          # text on the current line, do nothing.  Next time through the
          # main loop of _wrap_chunks(), we'll wind up here again, but
          # cur_len will be zero, so the next line will be entirely
          # devoted to the long word that we can't handle right now.
  
      def _wrap_chunks(self, chunks):
          """_wrap_chunks(chunks : [string]) -> [string]
  
          Wrap a sequence of text chunks and return a list of lines of
          length 'self.width' or less.  (If 'break_long_words' is false,
          some lines may be longer than this.)  Chunks correspond roughly
          to words and the whitespace between them: each chunk is
          indivisible (modulo 'break_long_words'), but a line break can
          come between any two chunks.  Chunks should not have internal
          whitespace; ie. a chunk is either all whitespace or a "word".
          Whitespace chunks will be removed from the beginning and end of
          lines, but apart from that whitespace is preserved.
          """
          lines = []
          if self.width <= 0:
              raise ValueError("invalid width %r (must be > 0)" % self.width)
          if self.max_lines is not None:
              if self.max_lines > 1:
                  indent = self.subsequent_indent
              else:
                  indent = self.initial_indent
              if len(indent) + len(self.placeholder.lstrip()) > self.width:
                  raise ValueError("placeholder too large for max width")
  
          # Arrange in reverse order so items can be efficiently popped
          # from a stack of chucks.
          chunks.reverse()
  
          while chunks:
  
              # Start the list of chunks that will make up the current line.
              # cur_len is just the length of all the chunks in cur_line.
              cur_line = []
              cur_len = 0
  
              # Figure out which static string will prefix this line.
              if lines:
                  indent = self.subsequent_indent
              else:
                  indent = self.initial_indent
  
              # Maximum width for this line.
              width = self.width - len(indent)
  
              # First chunk on line is whitespace -- drop it, unless this
              # is the very beginning of the text (ie. no lines started yet).
              if self.drop_whitespace and chunks[-1].strip() == '' and lines:
                  del chunks[-1]
  
              while chunks:
                  l = len(chunks[-1])
  
                  # Can at least squeeze this chunk onto the current line.
                  if cur_len + l <= width:
                      cur_line.append(chunks.pop())
                      cur_len += l
  
                  # Nope, this line is full.
                  else:
                      break
  
              # The current line is full, and the next chunk is too big to
              # fit on *any* line (not just this one).
              if chunks and len(chunks[-1]) > width:
                  self._handle_long_word(chunks, cur_line, cur_len, width)
                  cur_len = sum(map(len, cur_line))
  
              # If the last chunk on this line is all whitespace, drop it.
              if self.drop_whitespace and cur_line and cur_line[-1].strip() == '':
                  cur_len -= len(cur_line[-1])
                  del cur_line[-1]
  
              if cur_line:
                  if (self.max_lines is None or
                      len(lines) + 1 < self.max_lines or
                      (not chunks or
                       self.drop_whitespace and
                       len(chunks) == 1 and
                       not chunks[0].strip()) and cur_len <= width):
                      # Convert current line back to a string and store it in
                      # list of all lines (return value).
                      lines.append(indent + ''.join(cur_line))
                  else:
                      while cur_line:
                          if (cur_line[-1].strip() and
                              cur_len + len(self.placeholder) <= width):
                              cur_line.append(self.placeholder)
                              lines.append(indent + ''.join(cur_line))
                              break
                          cur_len -= len(cur_line[-1])
                          del cur_line[-1]
                      else:
                          if lines:
                              prev_line = lines[-1].rstrip()
                              if (len(prev_line) + len(self.placeholder) <=
                                      self.width):
                                  lines[-1] = prev_line + self.placeholder
                                  break
                          lines.append(indent + self.placeholder.lstrip())
                      break
  
          return lines
  
      def _split_chunks(self, text):
          text = self._munge_whitespace(text)
          return self._split(text)
  
      # -- Public interface ----------------------------------------------
  
      def wrap(self, text):
          """wrap(text : string) -> [string]
  
          Reformat the single paragraph in 'text' so it fits in lines of
          no more than 'self.width' columns, and return a list of wrapped
          lines.  Tabs in 'text' are expanded with string.expandtabs(),
          and all other whitespace characters (including newline) are
          converted to space.
          """
          chunks = self._split_chunks(text)
          if self.fix_sentence_endings:
              self._fix_sentence_endings(chunks)
          return self._wrap_chunks(chunks)
  
      def fill(self, text):
          """fill(text : string) -> string
  
          Reformat the single paragraph in 'text' to fit in lines of no
          more than 'self.width' columns, and return a new string
          containing the entire wrapped paragraph.
          """
          return "\n".join(self.wrap(text))
  
  
  # -- Convenience interface ---------------------------------------------
  
  def wrap(text, width=70, **kwargs):
      """Wrap a single paragraph of text, returning a list of wrapped lines.
  
      Reformat the single paragraph in 'text' so it fits in lines of no
      more than 'width' columns, and return a list of wrapped lines.  By
      default, tabs in 'text' are expanded with string.expandtabs(), and
      all other whitespace characters (including newline) are converted to
      space.  See TextWrapper class for available keyword args to customize
      wrapping behaviour.
      """
      w = TextWrapper(width=width, **kwargs)
      return w.wrap(text)
  
  def fill(text, width=70, **kwargs):
      """Fill a single paragraph of text, returning a new string.
  
      Reformat the single paragraph in 'text' to fit in lines of no more
      than 'width' columns, and return a new string containing the entire
      wrapped paragraph.  As with wrap(), tabs are expanded and other
      whitespace characters converted to space.  See TextWrapper class for
      available keyword args to customize wrapping behaviour.
      """
      w = TextWrapper(width=width, **kwargs)
      return w.fill(text)
  
  def shorten(text, width, **kwargs):
      """Collapse and truncate the given text to fit in the given width.
  
      The text first has its whitespace collapsed.  If it then fits in
      the *width*, it is returned as is.  Otherwise, as many words
      as possible are joined and then the placeholder is appended::
  
          >>> textwrap.shorten("Hello  world!", width=12)
          'Hello world!'
          >>> textwrap.shorten("Hello  world!", width=11)
          'Hello [...]'
      """
      w = TextWrapper(width=width, max_lines=1, **kwargs)
      return w.fill(' '.join(text.strip().split()))
  
  
  # -- Loosely related functionality -------------------------------------
  
  _whitespace_only_re = re.compile('^[ \t]+$', re.MULTILINE)
  _leading_whitespace_re = re.compile('(^[ \t]*)(?:[^ \t\n])', re.MULTILINE)
  
  def dedent(text):
      """Remove any common leading whitespace from every line in `text`.
  
      This can be used to make triple-quoted strings line up with the left
      edge of the display, while still presenting them in the source code
      in indented form.
  
      Note that tabs and spaces are both treated as whitespace, but they
      are not equal: the lines "  hello" and "\\thello" are
      considered to have no common leading whitespace.  (This behaviour is
      new in Python 2.5; older versions of this module incorrectly
      expanded tabs before searching for common leading whitespace.)
      """
      # Look for the longest leading string of spaces and tabs common to
      # all lines.
      margin = None
      text = _whitespace_only_re.sub('', text)
      indents = _leading_whitespace_re.findall(text)
      for indent in indents:
          if margin is None:
              margin = indent
  
          # Current line more deeply indented than previous winner:
          # no change (previous winner is still on top).
          elif indent.startswith(margin):
              pass
  
          # Current line consistent with and no deeper than previous winner:
          # it's the new winner.
          elif margin.startswith(indent):
              margin = indent
  
          # Find the largest common whitespace between current line and previous
          # winner.
          else:
              for i, (x, y) in enumerate(zip(margin, indent)):
                  if x != y:
                      margin = margin[:i]
                      break
              else:
                  margin = margin[:len(indent)]
  
      # sanity check (testing/debugging only)
      if 0 and margin:
          for line in text.split("\n"):
              assert not line or line.startswith(margin), \
                     "line = %r, margin = %r" % (line, margin)
  
      if margin:
          text = re.sub(r'(?m)^' + margin, '', text)
      return text
  
  
  def indent(text, prefix, predicate=None):
      """Adds 'prefix' to the beginning of selected lines in 'text'.
  
      If 'predicate' is provided, 'prefix' will only be added to the lines
      where 'predicate(line)' is True. If 'predicate' is not provided,
      it will default to adding 'prefix' to all non-empty lines that do not
      consist solely of whitespace characters.
      """
      if predicate is None:
          def predicate(line):
              return line.strip()
  
      def prefixed_lines():
          for line in text.splitlines(True):
              yield (prefix + line if predicate(line) else line)
      return ''.join(prefixed_lines())
  
  
  if __name__ == "__main__":
      #print dedent("\tfoo\n\tbar")
      #print dedent("  \thello there\n  \t  how are you?")
      print(dedent("Hello there.\n  This is indented."))
  