code: def _init_glyph(self, plot, mapping, properties):
          
          ret = super(ColorbarPlot, self)._init_glyph(plot, mapping, properties)
          if self.colorbar:
              for k, v in list(self.handles.items()):
                  if not k.endswith('color_mapper'):
                      continue
                  self._draw_colorbar(plot, v, k[:-12])
          return ret
docs: Returns a Bokeh glyph object and optionally creates a colorbar.