code: def on_train_begin(self, logs=None):
      if self.initial_lr is None:
          self.initial_lr = self.backend.get_value(
              self.model.optimizer.lr
          )
      if not self.staircase and not self.steps_per_epoch:
          self.steps_per_epoch = self._autodetect_steps_per_epoch()
  
imports: from packaging import version
  import warnings
  import horovod.tensorflow
  import tensorflow
label_desc: Use image node_id 5 for calling the LearningRateScheduleCallbackImpl obj's underlying member method code with example usage: obj.on_train_begin(logs) without return types