code: def test_init_trainer(self, ae, train_dataset, callbacks):
      trainer = BaseTrainer(model=ae, train_dataset=train_dataset)
  
      trainer.prepare_training()
  
      assert callbacks not in trainer.callback_handler.callbacks
  
      assert ProgressBarCallback().__class__ in [
          cb.__class__ for cb in trainer.callback_handler.callbacks
      ]
  
      trainer = BaseTrainer(
          model=ae, callbacks=[callbacks], train_dataset=train_dataset
      )
  
      trainer.prepare_training()
  
      assert callbacks in trainer.callback_handler.callbacks
  
      assert ProgressBarCallback().__class__ in [
          cb.__class__ for cb in trainer.callback_handler.callbacks
      ]
  
imports: import os
  from collections import Counter
  import pytest
  import torch
  from pythae.models import AE, RAE_L2, VAEGAN, Adversarial_AE, Adversarial_AE_Config, AEConfig, RAE_L2_Config, VAEGANConfig
  from pythae.trainers import *
  from pythae.trainers.training_callbacks import *
label_desc: Use image node_id 4 for calling the Test_TrainerCallbacks obj's underlying member method code with example usage: obj.test_init_trainer(ae, train_dataset, callbacks) without return types