If you looking for something short and simple, maybe it will be enough for you:
class A(object):
def __init__(self, l):
self.data = l
def __iter__(self):
return iter(self.data)
example of usage:
In [3]: a = A([2,3,4])
In [4]: [i for i in a]
Out[4]: [2, 3, 4]