class A():
    def __iter__(self):
        def _():
            return _
        return _
class B(A):
    pass

let a = A()
let b = B()

def __iter__(self):
    let o = 4
    def _():
        if o:
            return (o -= 1)
        return _
    return _

A.__iter__ = __iter__

for i in a:
    print(i)

for i in b:
    print(i)

# now what if we remove it
del A.__iter__

try:
    for i in b:
        print(i)
    print('did not raise attribute error')
except AttributeError:
    print('raised attribute error')