michael@0: a = {}
michael@0: function f(o) {
michael@0:     for (x in o) {
michael@0:         print
michael@0:     }
michael@0: }
michael@0: for (var i = 0; i < 3; i++) {
michael@0:     new f(a)
michael@0:     a.__proto__ = null
michael@0: }