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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def define_charset(self, code, mode):
 """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. """

        if code in cs.MAPS:
            if mode == "(":
                self.g0_charset = cs.MAPS[code]
            elif mode == ")":
                self.g1_charset = cs.MAPS[code]