code: def test_autoformer_forecaster_fit_loader_val(self):
      train_loader, val_loader, _ = create_data(loader=True)
      forecaster = AutoformerForecaster(
          past_seq_len=24,
          future_seq_len=5,
          input_feature_num=2,
          output_feature_num=2,
          label_len=12,
          freq="s",
          seed=0,
      )
      val_loss = forecaster.fit(train_loader, val_loader, epochs=10)
  
imports: import numpy
  import pandas
  import tempfile
  import os
  from bigdl.chronos.utils import LazyImport
  from bigdl.chronos.data import TSDataset
  from unittest import TestCase
  import pytest
  from ..None import op_torch, op_automl
label_desc: Use image node_id 20 for calling the TestChronosModelAutoformerForecaster obj's underlying member method code with example usage: obj.test_autoformer_forecaster_fit_loader_val() without return types