code: def test_individual_region_bars(self):
      df = pd.read_json(JSON_DF)
      chart = runtime_by_region_vis.individual_region_bars(
          df, title="chart title"
      )
      self.assertTrue(is_an_altair_chart(chart))
      chart_json = chart.to_json()
      self.assertIn("chart title", chart_json)
  
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 11 for calling the RuntimeByRegionVisTest obj's underlying member method code with example usage: obj.test_individual_region_bars() without return types