code: def test_selected_longest_and_median_regions(self):
      df = pd.read_json(JSON_DF)
      chart = runtime_by_region_vis.selected_longest_and_median_regions(
          df
      )
      self.assertTrue(is_an_altair_chart(chart))
  
imports: import io
  from absl.testing import absltest
  from absl.testing import parameterized
  import pandas
  from deepvariant import runtime_by_region_vis
  from deepvariant import testdata
label_desc: Use image node_id 8 for calling the RuntimeByRegionVisTest obj's underlying member method code with example usage: obj.test_selected_longest_and_median_regions() without return types