@Override
    public void xwrite_activated (Pipe pipe_)
    {
        for (Map.Entry<Blob, Outpipe> it: outpipes.entrySet()) {
            if (it.getValue().pipe == pipe_) {
                assert (!it.getValue().active);
                it.getValue().active = true;
                break;
            }
        }
        assert (false);
    }