human
I wrote the below code

    def _qsize(len=len):
        return 1
    def _put(item):
        pass
    def _get():
        return val
    if sync:
        q.mutex.acquire()
    try:
        q.maxsize = 2
        q._qsize = _qsize
        q._put = _put
        q._get = _get
        q.not_empty.notifyAll()
        q.not_full.notifyAll()
    finally:
        if sync:
            q.mutex.release()

What's a good function header?

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

def _invalidate_queue(q, val=None, sync=True):