code: def phi(x):
      # Feature extractor
      return np.asarray(x, dtype=np.float32) / 255
  
file_path: pfrl/examples/atari/train_a2c_ale.py
imports: import argparse
  import functools
  import logging
  import numpy
  from torch import nn
  import pfrl
  from pfrl import experiments, utils
  from pfrl.agents import a2c
  from pfrl.policies import SoftmaxCategoricalHead
  from pfrl.wrappers import atari_wrappers
label_desc: Use image node_id 1 for calling a global function with example usage: phi(x) and returns: unknown