code: def retrain(self):
          
          folder = TrainData.from_folder(self.args.folder)
          train_data, test_data = folder.load(True, not self.args.no_validation)
  
          train_data = TrainData.merge(train_data, self.sampled_data)
          test_data = TrainData.merge(test_data, self.test)
          train_inputs, train_outputs = train_data
          print()
          try:
              self.listener.runner.model.fit(
                  train_inputs, train_outputs, self.args.batch_size, self.epoch + self.args.epochs,
                  validation_data=test_data, callbacks=self.callbacks, initial_epoch=self.epoch
              )
          finally:
              self.listener.runner.model.save(self.args.model)
docs: Train for a session, pulling in any new data from the filesystem