class_docstr: A simple environment model.
class_docstr_tok: ["A","simple","environment","model","."]
code: def reset(self, initial_state: Optional[types.Observation] = None):
      if initial_state is None:
          raise ValueError("Model must be reset with an initial state.")
      # We reset to an initial state that we are explicitly given.
      # This allows us to handle environments with stochastic resets (e.g. Catch).
      self._state = initial_state.copy()
      self._needs_reset = False
      return dm_env.restart(self._state)
  
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 4 for calling the MLPModel obj's underlying member method code with example usage: obj.reset(initial_state) and returns: dm_env