code: def test_custom_stats(self):
      feature = statistics_pb2.FeatureNameStatistics()
      text_format.Parse(
          """
        custom_stats: {
          name: "stat1",
          str: "val1"
        }
        custom_stats: {
          name: "stat2",
          str: "val2"
        }
      """,
          feature,
      )
      view = stats_util.FeatureView(feature)
      self.assertEqual(view.custom_statistic("stat1").str, "val1")
      self.assertEqual(view.custom_statistic("stat2").str, "val2")
      self.assertIsNone(view.custom_statistic("stat3"))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  from absl import flags
  from absl.testing import absltest
  import numpy
  import tensorflow
  from tensorflow_data_validation import types
  from tensorflow_data_validation.utils import artifacts_io_impl
  from tensorflow_data_validation.utils import stats_util
  from google.protobuf import text_format
  from tensorflow.python.util.protobuf import compare
  from tensorflow_metadata.proto.v0 import statistics_pb2
label_desc: Use image node_id 5 for calling the FeatureViewTest obj's underlying member method code with example usage: obj.test_custom_stats() without return types