Can you give an example of how to use the listener?

[timblack1]

README.mkd says:

To define a new listener in your design doc:

{ ....

"changes":"var sys = require('sys');
           var listener = function (change) {
             sys.puts(JSON.stringify(change));
           }
           exports.listener = listener;",
}

I'm at a loss as to how to use this listener. Can you point me to an example of how to use it? I'm new to Node.js. Is there a general example of how to use a listener in the Node.js docs that would set me on the right path? I got here by watching this screencast: http://jsconf.eu/2010/speaker/nodejs_couchdb_crazy_delicious.html and searching for the changes listener Mikeal mentioned. Can you give a code snippet that shows the outlines of how to use the code above to notice that the database contains a new request to send an email? That's the gist of what I need to figure out, except instead of sending an email from Node, I'm trying to make an HTTP request.