code: def test_graph_op_edge_color(self):
      edges = [(0, 1, "red"), (0, 2, "green"), (1, 3, "blue")]
      graph = Graph(edges, vdims="color").opts(edge_color="color")
      plot = bokeh_renderer.get_plot(graph)
      cds = plot.handles["multi_line_1_source"]
      glyph = plot.handles["multi_line_1_glyph"]
      self.assertEqual(
          property_to_dict(glyph.line_color), {"field": "edge_color"}
      )
      self.assertEqual(
          cds.data["edge_color"], np.array(["red", "green", "blue"])
      )
  
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 23 for calling the TestBokehGraphPlot obj's underlying member method code with example usage: obj.test_graph_op_edge_color() without return types