code: def _find_latest_snapshot(fmt, path):
      """Finds the latest snapshots in a directory
  
      Args:
          fmt (str): format string to match with file names of
              existing snapshots, where prefix and suffix are
              only examined. Also, files' staleness is judged
              by timestamps. The default is metime.
          path (str): a directory path to search for snapshot files.
  
      Returns:
          Latest snapshot file, in terms of a file that has newest
          ``mtime`` that matches format ``fmt`` directly under
          ``path``. If no such file found, it returns ``None``.
  
      """
      snapshot_files = _find_snapshot_files(fmt, path)
  
      if len(snapshot_files) > 0:
          _, filename = snapshot_files[-1]
          return filename
  
      return None
  
imports: import os
  import warnings
  import chainer
  from chainer.serializers import npz
  from chainer.training import extension
  from chainer.training.extensions import snapshot_writers
  from chainer.utils import argument
label_desc: Use image node_id 2 for calling a global function with example usage: _find_latest_snapshot(fmt, path) and returns: None, filename