michael@0: 
michael@0: function foo(str) {
michael@0:   var x = eval(str); yield x[0];
michael@0: }
michael@0: for (var i = 0; i < 5; i++)
michael@0:   assertEq(foo("[4,5,6]").next(), 4);
michael@0: for (var i = 0; i < 5; i++)
michael@0:   assertEq(foo("arguments").next(), "arguments");