code: def test_label_linear_color_op(self):
      labels = Labels(
          [(0, 0, 0), (0, 1, 1), (0, 2, 2)], vdims="color"
      ).opts(color="color")
      plot = mpl_renderer.get_plot(labels)
      artist = plot.handles["artist"]
      self.assertEqual(
          [rgb2hex(a.get_color()) for a in artist],
          ["#440154", "#20908c", "#fde724"],
      )
  
imports: import numpy
  from holoviews.core.dimension import Dimension
  from holoviews.core.options import Cycle
  from holoviews.core.spaces import HoloMap
  from holoviews.element import Labels
  from holoviews.plotting.util import rgb2hex
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 8 for calling the TestLabelsPlot obj's underlying member method code with example usage: obj.test_label_linear_color_op() without return types