anchor.diff:                  ..type = compileType(context, CandyType.int)),
                 dart.Parameter((b) => b
                   ..name = 'item'
  -                ..type = t),
  +                ..type = item),
               ])
  -            ..returns = t
  +            ..returns = item
               ..body = dart
                   .refer('value')
                   .index(dart.refer('index.value'))
  
positive.code:           dart.Method((b) => b
              ..name = 'generate'
              ..static = true
              ..types.add(t)
              ..returns = arrayT
              ..requiredParameters.addAll([
                dart.Parameter((b) => b
                  ..name = 'length'
  
negative.code:             ..requiredParameters.add(dart.Parameter((b) => b
                ..name = 'index'
                ..type = compileType(context, CandyType.int)))
              ..returns = item
              ..body = dart.refer('value').index(dart.refer('index.value')).code),
            dart.Method((b) => b
              ..name = 'set'
  