docstr: This function will be called by the application engine at each
  iteration.
docstr_tok: ["This","function","will","be","called","by","the","application","engine","at","each","iteration","."]
code: def set_iteration_update(self, iteration_message):
      """
      This function will be called by the application engine at each
      iteration.
      """
      current_iter = iteration_message.current_iter
      if iteration_message.is_training:
          iteration_message.data_feed_dict[self.is_validation] = False
      elif iteration_message.is_validation:
          iteration_message.data_feed_dict[self.is_validation] = True
      iteration_message.data_feed_dict[
          self.learning_rate
      ] = self.current_lr
  
file_path: NiftyNet/demos/Learning_Rate_Decay/Demo_applications/no_decay_lr_comparison_application.py
imports: import tensorflow
  from niftynet.application.segmentation_application import SegmentationApplication
  from niftynet.engine.application_factory import OptimiserFactory
  from niftynet.engine.application_variables import CONSOLE
  from niftynet.engine.application_variables import TF_SUMMARIES
  from niftynet.layer.loss_segmentation import LossFunction
label_desc: Use image node_id 3 for calling the DecayLearningRateApplication obj's underlying member method code with example usage: obj.set_iteration_update(iteration_message) without return types