anchor.diff:  /// ```
   /// {@end-tool}
   // TODO(ianh): remove unreachable code above once https://github.com/dart-lang/sdk/issues/35520 is fixed
  -class FutureBuilder<T extends Object> extends StatefulWidget {
  +class FutureBuilder<T> extends StatefulWidget {
     /// Creates a widget that builds itself based on the latest snapshot of
     /// interaction with a [Future].
     ///
  
positive.code: ///  * [StreamBuilderBase], which supports widget building based on a computation
  ///    that spans all interactions made with the stream.
  // TODO(ianh): remove unreachable code above once https://github.com/dart-lang/linter/issues/1139 is fixed
  class StreamBuilder<T extends Object> extends StreamBuilderBase<T, AsyncSnapshot<T>> {
    /// Creates a new [StreamBuilder] that builds itself based on the latest
    /// snapshot of interaction with the specified [stream] and whose build
    /// strategy is given by [builder].
  
negative.code: }
  
  /// State for [FutureBuilder].
  class _FutureBuilderState<T> extends State<FutureBuilder<T>> {
    /// An object that identifies the currently active callbacks. Used to avoid
    /// calling setState from stale callbacks, e.g. after disposal of this state,
    /// or after widget reconfiguration to a new Future.
  