code: def running_mean_update(x, state):
      (mean, n) = state
      mean = n.astype(np.float32) / (n + 1) * mean + x / (n + 1)
      return (mean, n + 1)
  
file_path: trax/trax/rl/normalization.py
imports: import gin
  import numpy
  from trax import fastmath
  from trax import layers
label_desc: Use image node_id 2 for calling a global function with example usage: running_mean_update(x, state) and returns: mean,  unknown