Edit in JSFiddle

var Todo = new Class({
    Implements: Chain,
    initialize: function() {
        this.chain.apply(this, arguments);
    }
});

var myTodoList = new Todo(
    function() {
        $('log').set('text','get groceries');
    }, function() {
        $('log').set('text','go workout');
    }, function() {
        $('log').set('text','code mootools documentation until eyes close involuntarily');
    }, function() {
        $('log').set('text','sleep');
    }
);

<div id="log"></div>