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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 add_enclosure(self, left_char, right_char):
 """ Add new enclosure pair of characters. That and should be removed when their presence is detected at beginning and end of found URL :param str left_char: left character of enclosure pair - e.g. "(" :param str right_char: right character of enclosure pair - e.g. ")" """

        assert len(left_char) == 1, \
            "Parameter left_char must be character not string"
        assert len(right_char) == 1, \
            "Parameter right_char must be character not string"
        self._enclosure.add((left_char, right_char))

        self._after_tld_chars = self._get_after_tld_chars()