shut down the pool's workers

        this method sets the :attr:`closing` attribute, lines up the
        :attr:`closed` attribute to be set once any queued data has been
        processed, and raises a PoolClosed() exception in any coroutines still
        blocked on :meth:`get`.

def close(self):
        """shut down the pool's workers

        this method sets the :attr:`closing` attribute, lines up the
        :attr:`closed` attribute to be set once any queued data has been
        processed, and raises a PoolClosed() exception in any coroutines still
        blocked on :meth:`get`.
        """
        super(Pool, self).close()
        for waiter, waketime in self.outq._waiters:
            scheduler.schedule_exception(PoolClosed(), waiter)