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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 _check_reserved_characters(self, ustring):
 """ Check whether the given Unicode string contains reserved characters. :param string ustring: the string to be checked """

        forbidden = [c for c in gc.CONFIG_RESERVED_CHARACTERS if c in ustring]
        if len(forbidden) > 0:
            self._failed(u"The given string contains the reserved characters '%s'." % u" ".join(forbidden))