jQuery pub/sub plugin with context

jquery.pubsub.js

(function($) {
    var observer = $({});

    $.subscribe = function(topic, handler, context) {
        observer.on(topic, $.proxy(handler, context));
    };

    $.unsubscribe = function(topic, handler, context) {
        observer.off(topic, $.proxy(handler, context));
    };

    $.publish = function(topic) {
        observer.trigger.apply(observer, [topic].concat([Array.prototype.slice.call(arguments).slice(1)]));
    };
}(jQuery));