code: def define_charset(self, code, mode):
          
          if code in cs.MAPS:
              if mode == "(":
                  self.g0_charset = cs.MAPS[code]
              elif mode == ")":
                  self.g1_charset = cs.MAPS[code]
docs: Define ``G0`` or ``G1`` charset.
  
          :param str code: character set code, should be a character
                           from ``"B0UK"``, otherwise ignored.
          :param str mode: if ``"("`` ``G0`` charset is defined, if
                           ``")"`` -- we operate on ``G1``.
  
          .. warning:: User-defined charsets are currently not supported.