Occamsrazor.js 2.0 API ehnancement

I released version 2.0 of occamsrazor.js. My goal is to further simplify the API. This example is taken from my last post:

//mediator

var pubsub = occamsrazor();

// from now a validator is a simple function
var is_archive = function (obj){
    return 'getNumbers' in obj;
};

// the archive object

var archive = (function (){
    var numbers = [];
    return {
        getNumbers: function (){
            return numbers;
        },
        addItem: function (number){
            numbers.push(number);
            // this notify the event to the mediator
            pubsub.publish('changed', this);
        }
    };
}());

// the printsum isn't changed

var printsum = (function (){
    return {
        print: function (n){
            console.log(n);
        },
        sum_and_print: function (archive){
            var i,sum = 0;
            for(i = 0;i < archive.length; i++){
                sum += archive[i];
            }
            this.print(sum);
        }
    };
}());

// subscribe the event
// subscribe is an alias of "add" and "on"

// the list of validators now is before the function
pubsub.subscribe(["changed",is_archive], function (evt, archive){
    printsum.sum_and_print(archive.getNumbers());
});

//you can use a single string instead of a function as a validator