michael@0: // Removing and re-adding entries while an iterator is live causes the iterator to visit them again.
michael@0: 
michael@0: var set = Set(['a']);
michael@0: var n = 5;
michael@0: for (let v of set) {
michael@0:     assertEq(v, 'a');
michael@0:     if (n === 0)
michael@0:         break;
michael@0:     set.delete('a');
michael@0:     set.add('a');
michael@0:     n--;
michael@0: }
michael@0: assertEq(n, 0);