class_docstr: Base callback class. It defines the interface for callbacks.
code: def on_learn_epoch_end(self, epoch: int) -> None:
      pass
  
file_path: colossalai/applications/Chat/coati/trainer/callbacks/base.py
imports: from abc import ABC
  from coati.experience_maker import Experience
label_desc: Use image node_id 8 for calling the Callback obj's underlying member method code with example usage: obj.on_learn_epoch_end(epoch) without return types