class_docstr: Callback list that be executed.
  
  .. seealso::
      :class:`~neuraxle.metaopt.auto_ml.AutoML`,
      :class:`~neuraxle.metaopt.auto_ml.Trainer`,
      :class:`BaseCallback`,
code: def __getitem__(self, item):
      return self.callbacks[item]
  
imports: from abc import ABC, abstractmethod
  from typing import Callable, List, Optional
  from neuraxle.base import ExecutionContext
  from neuraxle.data_container import ARG_Y_EXPECTED, ARG_Y_PREDICTD, EvalEOTDACT
  from neuraxle.logging.warnings import warn_deprecated_class
  from neuraxle.metaopt.data.aggregates import MetricResults, TrialSplit
label_desc: Use image node_id 2 for calling the CallbackList obj's underlying member method code with example usage: obj.__getitem__(item) and returns: self