1import attr
2
3
4@attr.s
5class Obj(object):
6    x = attr.ib()
7    y = attr.ib(default=1)
8
9
10obj1 = Obj(2)
11assert(obj1.x == 2)
12assert(obj1.y == 1)
13obj2 = Obj(3, 4)
14assert(obj2.x == 3)
15assert(obj2.y == 4)
16