code: def test_multi_output_sum_loss(self):
      config = {
          "name": "multi_output_sum_loss",
          "loss": {"name": "mock_1"},
      }
      crit = build_loss(config)
      self.assertTrue(isinstance(crit, MultiOutputSumLoss))
  
      # test with a single output
      output = torch.tensor([1.0, 2.3])
      target = torch.tensor(1.0)
      self.assertAlmostEqual(crit(output, target).item(), 1.0)
  
      # test with a list of outputs
      output = [torch.tensor([1.2, 3.2])] * 5
      target = torch.tensor(2.3)
      self.assertAlmostEqual(crit(output, target).item(), 5.0)
  
file_path: ClassyVision/test/losses_multi_output_sum_loss_test.py
imports: import unittest
  import torch
  from classy_vision.losses import build_loss, ClassyLoss, MultiOutputSumLoss, register_loss
label_desc: Use image node_id 1 for calling the TestMultiOutputSumLoss obj's underlying member method code with example usage: obj.test_multi_output_sum_loss() without return types