code: def test_no_weight_feature(self):
      m = example_weight_map.ExampleWeightMap()
      self.assertIsNone(m.get(types.FeaturePath(["feature"])))
      self.assertEmpty(m.all_weight_features())
  
file_path: data-validation/tensorflow_data_validation/utils/example_weight_map_test.py
imports: from absl.testing import absltest
  from tensorflow_data_validation import types
  from tensorflow_data_validation.utils import example_weight_map
label_desc: Use image node_id 1 for calling the ExampleWeightMapTest obj's underlying member method code with example usage: obj.test_no_weight_feature() without return types