def __call__(self):
        """__call__"""
        time.sleep(0.1)  # pretend to take some time to do the work
        return "{} * {} = {}".format(self.a, self.b, self.a * self.b)
def __call__ ( self ) : time . sleep ( 0.1 ) return "{} * {} = {}" . format ( self . a , self . b , self . a * self . b )
__call__