Called in _collection to prepare results from redis before returning
        them.

def _prepare_results(self, results):
        """
        Called in _collection to prepare results from redis before returning
        them.
        """
        if self._instances:
            results = self._to_instances(results)
        else:
            results = list(results)

        # cache the len for future use
        self._len = len(results)

        return results