code: def test_schedule_dependent_on_previous_learning_rate(self):
      lr_scheduler = callbacks.LearningRateScheduler(
          lambda step, lr: lr / 2
      )
  
      initial_lr = 0.03
      self.model.compile(
          loss="mse",
          optimizer=optimizers.Adam(initial_lr),
      )
  
      self.model.fit(
          self.x_train,
          self.y_train,
          callbacks=[lr_scheduler],
          epochs=2,
      )
      self.assertEqual(
          self.model.optimizer.learning_rate.value, initial_lr / 4.0
      )
  
file_path: keras/keras/callbacks/learning_rate_scheduler_test.py
imports: import pytest
  from keras import callbacks
  from keras import layers
  from keras import optimizers
  from keras import testing
  from keras.models import Sequential
  from keras.testing import test_utils
  from keras.utils import io_utils
  from keras.utils import numerical_utils
label_desc: Use image node_id 4 for calling the LearningRateSchedulerTest obj's underlying member method code with example usage: obj.test_schedule_dependent_on_previous_learning_rate() without return types