Some python 2

    def flatten(x):
        def flatten_generator(x):
            if type(x) == list:
                for y in x:
                    for z in flatten(y):
                        yield z
            else:
                yield x
        return list(flatten_generator(x))

    assert(flatten([1, [2,3]]) == [1,2,3])

    ary = [1, [2,3], [4, [5,6]]]
    print flatten(ary)