docs: def check_color(option, opt, value):
      """Validate and convert an option value of type 'color'.
  
      ``option`` is an optparse.Option instance.
  
      ``opt`` is a string with the user-supplied option name (e.g. '--bgcolor').
  
      ``value`` is the user-supplied value.
      """
      try:
          return parse_color(value)
      except ValueError:
          raise optparse.OptionValueError("option %s: invalid color value: %r"
                                           % (opt, value))