anchor.diff:  /// Contains configuration for every possibility of provider, requiring that
   /// runtime injector implementations need to inspect the various properties and
   /// determine how to configure themselves.
  +@optionalTypeArgs
   @visibleForTesting
   class SlowProvider<T> implements Provider<T> {
     @override
  
positive.code: }
  
  /// An alias for `new Provider`; see [Provider].
  Provider provide(
    Object token, {
    Type useClass,
    Object useValue: noValueProvided,
  
negative.code: /// A [Provider] is a binding between a _token_ and an implementation that may
  /// be _provided_ either by invoking a constructor, a function, or referring to
  /// a literal value.
  @optionalTypeArgs
  abstract class Provider<T> implements RuntimeProvider<T> {
    const factory Provider(
      Object token, {
  