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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 failback(self, force_full_copy=None):
 """ Fails back a replication session. This can be applied on a replication session that is failed over. Fail back will synchronize the changes done to original destination back to original source site and will restore the original direction of session. :param force_full_copy: indicates whether to sync back all data from the destination SP to the source SP during the failback session. True - Sync back all data. False - Sync back changed data only. """

        req_body = self._cli.make_body(forceFullCopy=force_full_copy)
        resp = self.action('failback', **req_body)
        resp.raise_if_err()
        return resp