class_docstr: Computes the average undiscounted reward.
docstr: Resets stat gathering variables.
docstr_tok: ["Resets","stat","gathering","variables","."]
code: def _reset(self, batch_size):
      """Resets stat gathering variables."""
      self._np_state.episode_return = np.zeros(
          shape=(batch_size,), dtype=np.float64
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import abc
  from typing import Any, Iterable, Optional, Text
  import gin
  import numpy
  import six
  from tf_agents.metrics import py_metric
  from tf_agents.trajectories import trajectory
  from tf_agents.typing import types
  from tf_agents.utils import nest_utils
  from tf_agents.utils import numpy_storage
label_desc: Use image node_id 2 for calling the AverageReturnMetric obj's underlying member method code with example usage: obj._reset(batch_size) without return types