michael@0: function f(a, b) { return a + " " + b; }
michael@0: 
michael@0: for (var i = 0; i < 10; ++i) {
michael@0:     var s = '';
michael@0:     var a = {toString: function () { s += 'a'; return 'a'; }};
michael@0:     var b = {toString: function () { s += 'b'; return 'b'; }};
michael@0:     f(a, b);
michael@0:     assertEq(s, 'ab');
michael@0: }
michael@0: