code: def forward(self, batch, state=None, **kwargs):
      batch_size = batch.obs.cur_step.shape[0]
      if state is None:
          state = np.zeros(batch_size)
      else:
          state = state + 2
      return Batch(
          act=np.zeros(batch_size, dtype=np.int64), state=state
      )
  
file_path: nni/test/algo/nas/strategy/test_rl_impl.py
imports: from functools import partial
  import numpy
  import pytest
  from tianshou.data import ReplayBuffer, Batch
  from tianshou.policy import BasePolicy
  from nni.mutable import Categorical, Numerical, CategoricalMultiple, MutableDict, MutableList, ExpressionConstraint
  from nni.nas.strategy._rl_impl import TuningTrajectoryGenerator, default_policy_fn
label_desc: Use image node_id 2 for calling the HiddenStatePolicy obj's underlying member method code with example usage: obj.forward(batch, state) and returns: Batch