code: def test_violin_multi_level(self):
      box = Violin(
          (["A", "B"] * 15, [3, 10, 1] * 10, np.random.randn(30)),
          ["Group", "Category"],
          "Value",
      )
      plot = bokeh_renderer.get_plot(box)
      x_range = plot.handles["x_range"]
      self.assertEqual(
          x_range.factors,
          [
              ("A", "1"),
              ("A", "3"),
              ("A", "10"),
              ("B", "1"),
              ("B", "3"),
              ("B", "10"),
          ],
      )
  
imports: from unittest import SkipTest
  import numpy
  from bokeh.models import CategoricalColorMapper, LinearColorMapper
  from holoviews.element import Violin
  from holoviews.operation.stats import univariate_kde
  from holoviews.plotting.bokeh.util import property_to_dict
  from holoviews.util.transform import dim
  from .test_plot import TestBokehPlot, bokeh_renderer
label_desc: Use image node_id 3 for calling the TestBokehViolinPlot obj's underlying member method code with example usage: obj.test_violin_multi_level() without return types