What does this mean? node.js this.queue(String(Number(msg) ^ 1));

I'm investigating substack/shoe example code, especially node stream out out on browser side:

https://github.com/substack/shoe/blob/master/example/invert/client.js

stream.pipe(through(function (msg) {
    result.appendChild(document.createTextNode(msg));
    this.queue(String(Number(msg)^1));
})).pipe(stream);

I undersand what

result.appendChild(document.createTextNode(msg));

does, but I just can't figure out what

this.queue(String(Number(msg) ^ 1));

does along with

   .pipe(stream)

queue and .pipe(stream) back to stream slightly meaningful to me for stream control, but String(Number(msg) ^ 1) is the one I know nothing of. what is ^ 1)??