michael@0: // Inserting values in an array does not change the next index of an existing iterator.
michael@0: 
michael@0: var a = [1, 2, 3, 4];
michael@0: var s = '';
michael@0: for (var v of a) {
michael@0:     s += v;
michael@0:     if (s.length === 2)
michael@0:         a.unshift('x');
michael@0: }
michael@0: assertEq(s, '12234');