class_docstr: Call multiple callbacks at once.
class_docstr_tok: ["Call","multiple","callbacks","at","once","."]
docstr: Gets the state of all callbacks contained within this list.
  If there are no stateful callbacks, then None will be returned in order
  to avoid saving an unnecessary callback checkpoint file.
docstr_tok: ["Gets","the","state","of","all","callbacks","contained","within","this","list",".","If","there","are","no","stateful","callbacks",",","then","None","will","be","returned","in","order","to","avoid","saving","an","unnecessary","callback","checkpoint","file","."]
code: def get_state(self) -> Optional[Dict]:
      """Gets the state of all callbacks contained within this list.
      If there are no stateful callbacks, then None will be returned in order
      to avoid saving an unnecessary callback checkpoint file."""
      state = {}
      any_stateful_callbacks = False
      for i, callback in enumerate(self._callbacks):
          callback_state = callback.get_state()
          if callback_state:
              any_stateful_callbacks = True
          state[i] = callback_state
      if not any_stateful_callbacks:
          return None
      return state
  
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 14 for calling the CallbackList obj's underlying member method code with example usage: obj.get_state() and returns: state, None