anchor.diff:          test('multiple some', () {
             var log = [];
             iterable(['a', 'b', 'c']).forEachIndexedWhile((i, s) {
  -            log..add(i)..add(s);
  +            log
  +              ..add(i)
  +              ..add(s);
               return s != 'b';
             });
             expect(log, [0, 'a', 1, 'b']);
  
positive.code:         test('single', () {
            var log = [];
            ['a'].forEachIndexed((i, s) {
              log..add(i)..add(s);
            });
            expect(log, [0, 'a']);
          });
          test('multiple', () {
            var log = [];
            ['a', 'b', 'c'].forEachIndexed((i, s) {
              log..add(i)..add(s);
            });
            expect(log, [0, 'a', 1, 'b', 2, 'c']);
          });
  
negative.code:         test('multiple one', () {
            var log = [];
            iterable(['a', 'b', 'c']).forEachIndexedWhile((i, s) {
              log
                ..add(i)
                ..add(s);
              return false;
            });
            expect(log, [0, 'a']);
  