code: def test_lstm_forecaster_fit_loader_val(self):
      train_loader, val_loader, _ = create_data(loader=True)
      forecaster = LSTMForecaster(
          past_seq_len=24,
          input_feature_num=2,
          output_feature_num=2,
          hidden_dim=[32, 16],
          layer_num=2,
          dropout=[0.1, 0.2],
          loss="mae",
          lr=0.01,
      )
      val_loss = forecaster.fit(train_loader, val_loader, epochs=10)
  
imports: import numpy
  import tempfile
  import os
  from bigdl.chronos.utils import LazyImport
  from unittest import TestCase
  import pytest
  from ..None import op_torch, op_distributed, op_inference, op_automl
label_desc: Use image node_id 21 for calling the TestChronosModelLSTMForecaster obj's underlying member method code with example usage: obj.test_lstm_forecaster_fit_loader_val() without return types