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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 from_flag(cls, flag):
 """ Find relation implementation in the current charm, based on the name of an active flag. You should not use this method directly. Use :func:`endpoint_from_flag` instead. """

        value = _get_flag_value(flag)
        if value is None:
            return None
        relation_name = value['relation']
        conversations = Conversation.load(value['conversations'])
        return cls.from_name(relation_name, conversations)