human
Here's a good function header given the following:
I wrote the below code

    def gen(next, data={}, cnt=[0]):
        dpop = data.pop
        for i in itertools.count():
            if (i == cnt[0]):
                item = data[i] = next()
                cnt[0] += 1
            else:
                item = dpop(i)
            (yield item)
    next = iter(iterable).next
    return (gen(next), gen(next))

What's a good function header?
assistant
#Here's a good function header.

def compat_tee(iterable):