docs: def GetEncoding(self):
          '''Returns a string that can be used with the codecs python package
          to encode or decode the files in the chm archive. If an error is
          found, or if it is not possible to find the encoding, None is
          returned.'''
          if self.encoding:
              vals = string.split(self.encoding, ',')
              if len(vals) > 2:
                  try:
                      return charset_table[int(vals[2])]
                  except KeyError:
                      pass
          return None