code: def testAutoPivot_MetricsDataFrameStringifySlices(self):
      df = pd.DataFrame(
          {
              ("slices", "age"): [38.0, 38.0, None],
              ("slices", "sex"): [b"Female", b"Female", None],
              ("metric_keys", "name"): [
                  "mean_absolute_error",
                  "mean_squared_logarithmic_error",
                  "mean_absolute_error",
              ],
              ("metric_keys", "model_name"): ["", "", ""],
              ("metric_keys", "output_name"): ["", "", ""],
              ("metric_keys", "example_weighted"): [False, False, None],
              ("metric_keys", "is_diff"): [False, False, False],
              ("metric_values", "double_value"): [0.1, 0.02, 0.3],
          }
      )
      df = dataframe.auto_pivot(
          df, stringify_slices=True, collapse_column_names=False
      )
      mux = pd.MultiIndex.from_tuples(
          [
              (
                  ("metric_values", "double_value"),
                  np.nan,
                  "mean_absolute_error",
              ),
              (
                  ("metric_values", "double_value"),
                  False,
                  "mean_absolute_error",
              ),
              (
                  ("metric_values", "double_value"),
                  False,
                  "mean_squared_logarithmic_error",
              ),
          ],
          names=(
              None,
              ("metric_keys", "example_weighted"),
              ("metric_keys", "name"),
          ),
      )
      index = pd.Index(
          ["", "age:38.0; sex:b'Female'"], dtype="object", name="slices"
      )
      expected = pd.DataFrame(
          [[0.3, np.nan, np.nan], [np.nan, 0.1, 0.02]],
          index=index,
          columns=mux,
      )
      pd.testing.assert_frame_equal(expected, df)
  
imports: import dataclasses
  import numpy
  import pandas
  import tensorflow
  from tensorflow_model_analysis.experimental import dataframe
  from tensorflow_model_analysis.proto import metrics_for_slice_pb2
  from google.protobuf import text_format
label_desc: Use image node_id 7 for calling the MetricsAsDataFrameTest obj's underlying member method code with example usage: obj.testAutoPivot_MetricsDataFrameStringifySlices() without return types