class_docstr: A trigger specifies a timespot or several timespots during training,
  and a corresponding action will be taken when the timespot(s) is reached.
  EveryEpoch is a trigger that triggers an action when each epoch finishs.
  Could be used as trigger in setvalidation and setcheckpoint in Optimizer,
  and also in TrainSummary.set_summary_trigger.
  
  
  >>> everyEpoch = EveryEpoch()
code: def get_trigger(self) -> "DLlibEveryEpoch":
      return self.trigger
  
file_path: BigDL/python/orca/src/bigdl/orca/learn/trigger.py
imports: from abc import ABC, abstractmethod
  from typing import TYPE_CHECKING
  from typing import Union, Optional
label_desc: Use image node_id 2 for calling the EveryEpoch obj's underlying member method code with example usage: obj.get_trigger() and returns: self