Python階級之：call

# 功能需求：對實例的調用要像函數一樣
# 採用 __call__

class Point(object):
    def __init__(self,x,y):
        self.x,self.y = x,y
    def __call__(self, z):
        return self.x + self.y + z

p = Point(3,4)
print(callable(p))
print(p(6))