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

    def _chunk_iterator(first):
        v = first
        while (v != split_value):
            (yield v)
            v = it.next()
    while True:
        (yield _chunk_iterator(it.next()))

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

def split_at(it, split_value):