code: def _init_glyph(self, plot, mapping, properties):
          
          properties.pop('legend', None)
          for prop in ['color', 'alpha']:
              if prop not in properties:
                  continue
              pval = properties.pop(prop)
              line_prop = 'line_%s' % prop
              fill_prop = 'fill_%s' % prop
              if line_prop not in properties:
                  properties[line_prop] = pval
              if fill_prop not in properties and fill_prop in self.style_opts:
                  properties[fill_prop] = pval
          properties = mpl_to_bokeh(properties)
          plot_method = self._plot_methods['single']
          glyph = plot_method(**dict(properties, **mapping))
          plot.add_layout(glyph)
          return None, glyph
docs: Returns a Bokeh glyph object.