code: def test__lr_scheduler(self):
      lr = self.trainer._lr_scheduler(epoch=10)
      expected_lr = 0.0004 * (0.5) ** 2
      self.assertTrue(lr == expected_lr)
  
imports: import logging
  import os
  import shutil
  import unittest
  from copy import copy
  from pathlib import Path
  import yaml
  import numpy
  from unittest.mock import patch, Mock
  from ISR.models.cut_vgg19 import Cut_VGG19
  from ISR.models.discriminator import Discriminator
  from ISR.models.rrdn import RRDN
  from ISR.train.trainer import Trainer
label_desc: Use image node_id 6 for calling the TrainerClassTest obj's underlying member method code with example usage: obj.test__lr_scheduler() without return types