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

    def _chunk_iter():
        offset = len(text)
        while True:
            offset -= (chunk_size * 1024)
            if (offset <= 0):
                break
            (yield (text[offset:], offset))
        (yield (text, 0))
    pattern = (re.compile(pattern) if isinstance(pattern, basestring) else pattern)
    for (chunk, offset) in _chunk_iter():
        matches = [match for match in pattern.finditer(chunk)]
        if matches:
            return ((offset + matches[(-1)].span()[0]), (offset + matches[(-1)].span()[1]))
    return None

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

def re_rsearch(pattern, text, chunk_size=1024):