code: def aesthetics(cls):
          
          main = cls.DEFAULT_AES.keys() | cls.REQUIRED_AES
          other = {'group'}
          # Need to recognize both spellings
          if 'color' in main:
              other.add('colour')
          if 'outlier_color' in main:
              other.add('outlier_colour')
          return main | other
docs: Return all the aesthetics for this geom
  
          geoms should not override this method.