docs: def _set_transmaps(self):
          """Set translation maps for our standard."""
          if self._std == 'ascii':
              self._lower_chars = string.ascii_lowercase
              self._upper_chars = string.ascii_uppercase
  
          elif self._std == 'rfc1459':
              self._lower_chars = (string.ascii_lowercase +
                                   ''.join(chr(i) for i in range(123, 127)))
              self._upper_chars = (string.ascii_uppercase +
                                   ''.join(chr(i) for i in range(91, 95)))
  
          elif self._std == 'rfc1459-strict':
              self._lower_chars = (string.ascii_lowercase +
                                   ''.join(chr(i) for i in range(123, 126)))
              self._upper_chars = (string.ascii_uppercase +
                                   ''.join(chr(i) for i in range(91, 94)))