michael@0: // Nested for-of loops can iterate over a Set.
michael@0: 
michael@0: var map = Set(['a', 'b']);
michael@0: var log = '';
michael@0: for (let x of map) {
michael@0:     log += x + ':'
michael@0:     for (let y of map)
michael@0:         log += y;
michael@0:     log += ';'
michael@0: };
michael@0: assertEq(log, 'a:ab;b:ab;');