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

    fillvalue = kwds.get('fillvalue')
    def sentinel(counter=([fillvalue] * (len(args) - 1)).pop):
        (yield counter())
    fillers = itertools.repeat(fillvalue)
    iters = [itertools.chain(it, sentinel(), fillers) for it in args]
    try:
        for tup in itertools.izip(*iters):
            (yield tup)
    except IndexError:
        pass

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

def _izip_longest(*args, **kwds):