old_contents: # Copyright © 2015 Jakub Wilk <jwilk@jwilk.net>
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the “Software”), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  
  '''
  color terminal support
  '''
  
  import io
  import itertools
  import unicodedata
  
  class _seq:
      dim = '\x1B[1;30m'
      off = '\x1B[0m'
      warn = '\x1B[30;43m'
      error = '\x1B[30;41m'
      reverse = '\x1B[7m'
      unreverse = '\x1B[27m'
  
  def dim(s):
      return _seq.dim + escape(s) + _seq.off
  
  def escape(s):
      return highlight(s, itertools.repeat('off'))
  
  def highlight(s, w):
      if isinstance(w, str):
          w = itertools.repeat(w)
      fp = io.StringIO()
      off = _seq.off
      old_color = off
      for (cs, cw) in zip(s, w):
          color = getattr(_seq, cw)
          if color != old_color:
              fp.write(color)
              old_color = color
          if unicodedata.category(cs) == 'Cc':
              if cs < ' ' or cs == '\x7F':
                  cs = '^' + chr(ord(cs) ^ ord('@'))
              else:
                  cs = '<U+{0:04X}>'.format(ord(cs))
              cs = '{t.reverse}{c}{t.unreverse}'.format(c=cs, t=_seq)
          fp.write(cs)
      if old_color != off:
          fp.write(off)
      return fp.getvalue()
  
  __all__ = [
      'dim',
      'escape',
      'highlight',
  ]
  
  # vim:ts=4 sts=4 sw=4 et
  
new_contents: # Copyright © 2015 Jakub Wilk <jwilk@jwilk.net>
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the “Software”), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  
  '''
  color terminal support
  '''
  
  import io
  import itertools
  import unicodedata
  
  class _seq:
      dim = '\x1B[90m'
      off = '\x1B[0m'
      warn = '\x1B[30;43m'
      error = '\x1B[30;41m'
      reverse = '\x1B[7m'
      unreverse = '\x1B[27m'
  
  def dim(s):
      return _seq.dim + escape(s) + _seq.off
  
  def escape(s):
      return highlight(s, itertools.repeat('off'))
  
  def highlight(s, w):
      if isinstance(w, str):
          w = itertools.repeat(w)
      fp = io.StringIO()
      off = _seq.off
      old_color = off
      for (cs, cw) in zip(s, w):
          color = getattr(_seq, cw)
          if color != old_color:
              fp.write(color)
              old_color = color
          if unicodedata.category(cs) == 'Cc':
              if cs < ' ' or cs == '\x7F':
                  cs = '^' + chr(ord(cs) ^ ord('@'))
              else:
                  cs = '<U+{0:04X}>'.format(ord(cs))
              cs = '{t.reverse}{c}{t.unreverse}'.format(c=cs, t=_seq)
          fp.write(cs)
      if old_color != off:
          fp.write(off)
      return fp.getvalue()
  
  __all__ = [
      'dim',
      'escape',
      'highlight',
  ]
  
  # vim:ts=4 sts=4 sw=4 et
  
subject: use \e[90m for dark gray.