code: def test_abs(self):
      def mean_absolute_error(y_true, y_pred):
          result = mean(abs(y_true - y_pred), axis=1)
          return result
  
      self.compareLossWithKeras(
          kloss.mean_absolute_error,
          CustomLoss(mean_absolute_error, [3]),
          [2, 3],
          sizeAverageKerasLoss=True,
      )
  
file_path: analytics-zoo/pyzoo/test/zoo/pipeline/autograd/test_loss.py
imports: import keras.backend
  import keras.layers
  import keras.objectives
  import pytest
  from test.zoo.pipeline.utils.test_utils import ZooTestCase
  from zoo.pipeline.api.autograd import *
  from zoo.pipeline.api.keras.models import *
  from zoo.pipeline.api.keras.layers import *
label_desc: Use image node_id 2 for calling the TestLoss obj's underlying member method code with example usage: obj.test_abs() and returns: result