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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 previous(self):
 """Return a copy of this object as was at its previous state in history. Returns None if this object is new (and therefore has no history). The returned object is always "disconnected", i.e. does not receive live updates. """

        return self.model.state.get_entity(
            self.entity_type, self.entity_id, self._history_index - 1,
            connected=False)