gistfile1.js

>>> var a = new Class({method: function() { console.log(1) }})
>>> var b = new Class({Extends: a, method: function() { console.log(2); this.parent(); }})
>>> var c = new Class({Extends: b})
>>> (new c).method(0)
2
1
>>> Class.refactor(c, {method: function() { this.previous(); console.log('c') }})
function()
>>> (new c).method(0)
2
2
1
c