code: def _get_codepage_char_map(self, encoding):
          
          # Skip things that were loaded previously
          if encoding in self.available_characters:
              return self.available_characters[encoding]
          codepage_char_list = self._get_codepage_char_list(encoding)
          codepage_char_map = dict((utf8, i + 128) for (i, utf8) in enumerate(codepage_char_list))
          self.available_characters[encoding] = codepage_char_map
          return codepage_char_map
docs: Get codepage character map
  
          Process an encoding and return a map of UTF-characters to code points
          in this encoding.
  
          This is generated once only, and returned from a cache.
  
          :param encoding: The name of the encoding.