code: def test_train_step(self):
      batch_size = BATCH_SIZE
      (
          input_dummy,
          input_lengths,
          mel_spec,
          mel_lengths,
          speaker_ids,
      ) = self._create_inputs(batch_size)
      criterion = GlowTTSLoss()
      # model to train
      config = GlowTTSConfig(num_chars=32)
      model = GlowTTS(config).to(device)
      # reference model to compare model weights
      model_ref = GlowTTS(config).to(device)
      model.train()
      print(
          " > Num parameters for GlowTTS model:%s"
          % (count_parameters(model))
      )
      # pass the state to ref model
      model_ref.load_state_dict(copy.deepcopy(model.state_dict()))
      count = 0
      for param, param_ref in zip(
          model.parameters(), model_ref.parameters()
      ):
          assert (param - param_ref).sum() == 0, param
          count += 1
      optimizer = optim.Adam(model.parameters(), lr=0.001)
      for _ in range(5):
          optimizer.zero_grad()
          outputs = model.forward(
              input_dummy, input_lengths, mel_spec, mel_lengths, None
          )
          loss_dict = criterion(
              outputs["z"],
              outputs["y_mean"],
              outputs["y_log_scale"],
              outputs["logdet"],
              mel_lengths,
              outputs["durations_log"],
              outputs["total_durations_log"],
              input_lengths,
          )
          loss = loss_dict["loss"]
          loss.backward()
          optimizer.step()
      # check parameter changes
      self._check_parameter_changes(model, model_ref)
  
imports: import copy
  import os
  import unittest
  import torch
  from torch import optim
  from trainer.logging.tensorboard_logger import TensorboardLogger
  from tests import get_tests_data_path, get_tests_input_path, get_tests_output_path
  from TTS.tts.configs.glow_tts_config import GlowTTSConfig
  from TTS.tts.layers.losses import GlowTTSLoss
  from TTS.tts.models.glow_tts import GlowTTS
  from TTS.tts.utils.speakers import SpeakerManager
  from TTS.utils.audio import AudioProcessor
label_desc: Use image node_id 21 for calling the TestGlowTTS obj's underlying member method code with example usage: obj.test_train_step() without return types