def exclusive(via=threading.Lock):
    """pass"""

    def make_exclusive(fnc):
        fnc_guard = via()

        @functools.wraps(fnc)
        def exclusive_call(*args, **kwargs):
            if fnc_guard.acquire(blocking=False):
                try:
                    return fnc(*args, **kwargs)
                finally:
                    fnc_guard.release()
            else:
                raise RuntimeError('exclusive call to %s violated')
        return exclusive_call
    return make_exclusive