('Point', ['x', 'y', 'z']) #创建具名元组类
>>> Point
>>> p = Point(3, 4, 5) #实例化对象..._replace(x=30, z=8) #替换成员值,返回新对象
Point(x=30, y=4, z=8)
>>> p
Point(x=3, y=4, z=5)
>>> p.x = 7 #不允许这样直接赋值...AttributeError: can't set attribute
>>> hash(p) #可哈希
5050912105994302585
>>> x = dict()
>>> x[p] =