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

    client = AsyncHTTPClient()
    @gen.coroutine
    def is_reachable():
        try:
            r = (yield client.fetch(url, follow_redirects=False))
            return r
        except HTTPError as e:
            if (e.code >= 500):
                if (e.code != 599):
                    app_log.warning('Server    at    %s    responded    with    error:    %s', url, e.code)
            else:
                app_log.debug('Server    at    %s    responded    with    %s', url, e.code)
                return e.response
        except (OSError, socket.error) as e:
            if (e.errno not in {errno.ECONNABORTED, errno.ECONNREFUSED, errno.ECONNRESET}):
                app_log.warning('Failed    to    connect    to    %s    (%s)', url, e)
        return False
    re = (yield exponential_backoff(is_reachable, "Server    at    {url}    didn't    respond    in    {timeout}    seconds".format(url=url, timeout=timeout)))
    return re

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

@gen.coroutine
def wait_for_http_server(url, timeout=10):