def darken(self, color, diff, *args):
        """ Darken a color
        args:
            color (str): color
            diff (str): percentage
        returns:
            str
        """
        if color and diff:
            return self._ophsl(color, diff, 1, operator.sub)
        raise ValueError('Illegal color values')
def darken ( self , color , diff , * args ) : if color and diff : return self . _ophsl ( color , diff , 1 , operator . sub ) raise ValueError ( 'Illegal color values' )
Darken a color
        args:
            color (str): color
            diff (str): percentage
        returns:
            str