Return batch with given indexes

def _get_transitions(self, indexes):
        """ Return batch with given indexes """
        transition_tensors = self.backend.get_transitions(indexes)

        return Trajectories(
            num_steps=indexes.shape[0],
            num_envs=indexes.shape[1],
            environment_information=None,
            transition_tensors=transition_tensors,
            rollout_tensors={}
        ).to_transitions()