class Foo:
    def __init__(self, len: int):
        self.len = len
    
    def __getitem__(self, key: int):
        return key
    
    def __len__(self):
        return self.len

for i in Foo(12):
    print(i)

    if i > 1000:
        break

print(*reversed(Foo(12)), sep = " ")

Foo.__len__ = lambda self: self.len ** 2

print(*reversed(Foo(12)), sep = " ")