michael@0: // Generator-iterators are consumed the first time they are iterated.
michael@0: 
michael@0: function range(n) {
michael@0:     for (var i = 0; i < n; i++)
michael@0:         yield i;
michael@0: }
michael@0: 
michael@0: var r = range(10);
michael@0: var i = 0;
michael@0: for (var x in r)
michael@0:     assertEq(x, i++);
michael@0: assertEq(i, 10);
michael@0: for (var y in r)
michael@0:     throw "FAIL";
michael@0: assertEq(y, undefined);