code: def test_get_custom_stats_not_found(self):
      stats = text_format.Parse(
          """
              name: 'feature'
              custom_stats {
                name: 'abc'
                num: 100.0
              }
          """,
          statistics_pb2.FeatureNameStatistics(),
      )
      with self.assertRaisesRegex(
          ValueError, "Custom statistics.*not found"
      ):
          stats_util.get_custom_stats(stats, "xyz")
  
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 13 for calling the StatsUtilTest obj's underlying member method code with example usage: obj.test_get_custom_stats_not_found() without return types