code: def test_train(self):
      trainer = Trainer(self.model, preprocessor=self.p)
      trainer.train(
          self.x_train,
          self.y_train,
          x_valid=self.x_valid,
          y_valid=self.y_valid,
      )
  
file_path: anago/tests/test_trainer.py
imports: import os
  import unittest
  from anago.utils import load_data_and_labels
  from anago.models import BiLSTMCRF, save_model
  from anago.preprocessing import IndexTransformer
  from anago.trainer import Trainer
label_desc: Use image node_id 3 for calling the TestTrainer obj's underlying member method code with example usage: obj.test_train() without return types