code: def preprocess_step(ts: dm_env.TimeStep) -> dm_env.TimeStep:
      # reward: None -> 0, discount: None -> 1,
      # scalar -> np.array(), and StepType -> int.
      if ts.reward is None:
          ts = ts._replace(reward=0.0)
      if ts.discount is None:
          ts = ts._replace(discount=1.0)
      return jax.tree_util.tree_map(np.asarray, ts)
  
imports: import functools
  import queue
  import threading
  from typing import Any, Callable, NamedTuple
  from absl import app
  from absl import logging
  from bsuite.environments import catch
  import dm_env
  import haiku
  import jax
  import jax.numpy
  import numpy
  import optax
  import rlax
label_desc: Use image node_id 1 for calling a global function with example usage: preprocess_step(ts) and returns: jax