class_docstr: A sequence of statuses of trials as they progress.
  
  If all trials keep previous status, no snapshot is taken.
docstr: May append a new snapshot to the sequence.
docstr_tok: ["May","append","a","new","snapshot","to","the","sequence","."]
code: def append(self, new_snapshot: Dict[str, str]):
      """May append a new snapshot to the sequence."""
      if not new_snapshot:
          # Don't add an empty snapshot.
          return
      if not self._snapshot or new_snapshot != self._snapshot[-1]:
          self._snapshot.append(new_snapshot)
  
imports: from collections import defaultdict
  import logging
  import os
  import random
  import time
  from pathlib import Path
  from typing import Dict
  from ray.tune.callback import Callback
  from ray.tune.experiment import Trial
label_desc: Use image node_id 2 for calling the TrialStatusSnapshot obj's underlying member method code with example usage: obj.append(new_snapshot) without return types