code: def create_geoms(self, plot):
          
          for l in plot.layers:
              exclude = set()
              if isinstance(l.show_legend, dict):
                  l.show_legend = rename_aesthetics(l.show_legend)
                  exclude = {ae for ae, val in l.show_legend.items()
                             if not val}
              elif l.show_legend not in (None, True):
                  continue
  
              matched = self.legend_aesthetics(l, plot)
  
              # layer uses guide
              if set(matched) - exclude:
                  break
          # no break, no layer uses this guide
          else:
              return None
  
          return self
docs: This guide is not geom based
  
          Return self if colorbar will be drawn and None if not.