code: def test_graph_nodes_categorical_colormapped(self):
      g = self.graph2.opts(color_index="Label", cmap="Set1")
      plot = bokeh_renderer.get_plot(g)
      cmapper = plot.handles["color_mapper"]
      node_source = plot.handles["scatter_1_source"]
      glyph = plot.handles["scatter_1_glyph"]
      self.assertIsInstance(cmapper, CategoricalColorMapper)
      self.assertEqual(cmapper.factors, ["Output", "Input"])
      self.assertEqual(
          node_source.data["Label"], self.node_info["Label"]
      )
      self.assertEqual(
          property_to_dict(glyph.fill_color),
          {"field": "Label", "transform": cmapper},
      )
  
imports: import numpy
  from bokeh.models import EdgesAndLinkedNodes, NodesAndLinkedEdges, NodesOnly, Patches
  from bokeh.models.mappers import CategoricalColorMapper, LinearColorMapper
  from holoviews.core.data import Dataset
  from holoviews.element import Chord, Graph, Nodes, TriMesh, VLine, circular_layout
  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 12 for calling the TestBokehGraphPlot obj's underlying member method code with example usage: obj.test_graph_nodes_categorical_colormapped() without return types