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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 pack(self, value=None):
 """Pack and complete the last byte by padding."""

        if isinstance(value, Match):
            return value.pack()
        elif value is None:
            self._update_match_length()
            packet = super().pack()
            return self._complete_last_byte(packet)
        raise PackException(f'Match can\'t unpack "{value}".')