def fail(self, tup_id):
pass<EOL>
Called when a Tuple fails in the topology

        A spout can choose to emit the Tuple again or ignore the fail. The
        default is to ignore.

        :param tup_id: the ID of the Tuple that has failed in the topology
                       either due to a bolt calling ``fail()`` or a Tuple
                       timing out.
        :type tup_id: str