code: def __init__(self, shape=()):
      self.num_pushes = 0
      self.mean_array = np.zeros(shape)
      self.std_array = np.zeros(shape)
  
imports: import logging
  import threading
  import numpy
  import tree
  from ray.rllib.utils.annotations import DeveloperAPI
  from ray.rllib.utils.deprecation import Deprecated
  from ray.rllib.utils.numpy import SMALL_NUMBER
  from ray.rllib.utils.typing import TensorStructType
  from ray.rllib.utils.serialization import _serialize_ndarray, _deserialize_ndarray
  from ray.rllib.utils.deprecation import deprecation_warning
label_desc: Use image node_id 1 to create a new RunningStat object  with example: obj = RunningStat(shape)