class_docstr: Call multiple callbacks at once.
class_docstr_tok: ["Call","multiple","callbacks","at","once","."]
code: def on_step_end(self, **info):
      for callback in self._callbacks:
          callback.on_step_end(**info)
  
imports: from abc import ABCMeta
  import glob
  import os
  from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple
  import warnings
  from ray.util.annotations import PublicAPI, DeveloperAPI
  from ray.tune.utils.util import _atomic_save, _load_newest_checkpoint
label_desc: Use image node_id 4 for calling the CallbackList obj's underlying member method code with example usage: obj.on_step_end() without return types