@classmethod
def aesthetics(cls):
    """
        Return all the aesthetics for this geom

        geoms should not override this method.
        """
    main = cls.DEFAULT_AES.keys() | cls.REQUIRED_AES
    other = {'group'}
    if 'color' in main:
        other.add('colour')
    if 'outlier_color' in main:
        other.add('outlier_colour')
    return main | other
