class_docstr: Counts the number of episodes in the environment.
code: def result(self) -> np.int64:
      return self._np_state.number_episodes
  
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 3 for calling the NumberOfEpisodes obj's underlying member method code with example usage: obj.result() and returns: self