code: def _build_test_series(
      self, shape, freq, start="2020-01-01 00:00:00"
  ):
      values = self.evaluate(
          tf.random.stateless_normal(
              shape, seed=test_util.test_seed(sampler_type="stateless")
          )
      )
      index = pd.date_range(
          "2020-01-01 00:00:00", periods=shape[0], freq=freq
      )
      if len(shape) > 1:
          num_columns = shape[1]
          return pd.DataFrame(
              values,
              columns=[
                  "series{}".format(i) for i in range(num_columns)
              ],
              index=index,
          )
      else:
          return pd.Series(values, index=index)
  
file_path: probability/tensorflow_probability/python/sts/anomaly_detection/anomaly_detection_test.py
imports: from absl.testing import parameterized
  import numpy
  import pandas
  import tensorflow.compat.v2
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.sts import anomaly_detection
label_desc: Use image node_id 1 for calling the AnomalyDetectionTests obj's underlying member method code with example usage: obj._build_test_series(shape, freq, start) and returns: pd, pd