code: def _checkpoint_path_step(path: str) -> Optional[float]:
      """Returns the step number of a checkpoint path."""
      for s in SIGNED_FLOAT_RE.split(path)[::-1]:
          if SIGNED_FLOAT_RE.match(s):
              return float(s)
      return None
  
imports: import functools
  import os
  import pathlib
  import re
  import time
  import warnings
  from concurrent.futures import thread
  from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Type, Union
  import jax
  import orbax.checkpoint
  from absl import logging
  from jax import monitoring, process_index
  from jax import tree_util
  from jax.experimental.array_serialization.serialization import GlobalAsyncCheckpointManager, get_tensorstore_spec
  from jax.experimental.multihost_utils import sync_global_devices
  from flax import config, core, errors, io, serialization, traverse_util
  from flax.training import orbax_utils
label_desc: Use image node_id 3 for calling a global function with example usage: _checkpoint_path_step(path) and returns: None, float