class_docstr: A simple environment model.
class_docstr_tok: ["A","simple","environment","model","."]
code: def save_checkpoint(self):
      if self._needs_reset:
          raise ValueError(
              "Cannot save checkpoint: model must be reset first."
          )
      self._checkpoint = self._state.copy()
  
imports: from typing import Optional, Tuple
  from acme import specs
  from acme.agents.tf.mcts import types
  from acme.agents.tf.mcts.models import base
  from acme.tf import utils
  from bsuite.baselines.utils import replay
  import dm_env
  import numpy
  from scipy import special
  import sonnet
  import tensorflow
label_desc: Use image node_id 6 for calling the MLPModel obj's underlying member method code with example usage: obj.save_checkpoint() without return types