code: def test_get_default_mapping(self):
      # check for presence of glyphs in mapping
      # there is no sense in checking the default mapping here again
      # because it is basically a definition
  
      glyphs = self.plot._style_groups.keys()
      glyphs_mapped = self.plot.get_default_mapping(None, None).keys()
      glyphs_plain = {x[:-2] for x in glyphs_mapped}
  
      self.assertTrue(all([x in glyphs_plain for x in glyphs]))
  
imports: from itertools import product
  import numpy
  from bokeh.models import ColorBar
  from holoviews.core.spaces import HoloMap
  from holoviews.element.raster import HeatMap
  from holoviews.plotting.bokeh import RadialHeatMapPlot
  from .test_plot import TestBokehPlot, bokeh_renderer
label_desc: Use image node_id 8 for calling the BokehRadialHeatMapPlotTests obj's underlying member method code with example usage: obj.test_get_default_mapping() without return types