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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 _process_tags(self, tags):
 """Process the tags of the message :param tags: the tags string of a message :type tags: :class:`str` | None :returns: list of tags :rtype: :class:`list` of :class:`message.Tag` :raises: None """

        if not tags:
            return []
        return [message.Tag.from_str(x) for x in tags.split(';')]