Javascript operator overload? (def.js)

Question

Possible duplicate:
Javascript syntax I haven & rsquo; t seen so far, what is he really doing?

Just saw http://github.com/tobeytailor/def.js today and I don’t understand how this works:

def ("Ninja") << Person ({
    init: function(name){
        this._super();
    },

    kick: function(){
        this.speak("I kick u!");
    }
});

Looking through the code for def.js, I do not see anything mentioning the operator <<. How does this pseudo-operator overload?