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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 post(self, text=None, attachments=None, source_guid=None):
 """Post a direct message to the user. :param str text: the message content :param attachments: message attachments :param str source_guid: a client-side unique ID for the message :return: the message sent :rtype: :class:`~groupy.api.messages.DirectMessage` """

        return self.messages.create(text=text, attachments=attachments,
                                    source_guid=source_guid)