anchor.diff:    return digit1 * 16 + digit2 - (digit2 & 256);
   }
   
  -/// A resusable `null`-valued future used by `dart:async`.
  +/// A reusable `null`-valued future used by `dart:async`.
   ///
   /// **DO NOT USE.**
   ///
  
positive.code: /// Can be used internally in platform library implementations of
  /// data structures, where a value is known to have a type different
  /// from its static type (like knowing that a string is definitely
  /// a "_OneByteString" or that the value stored into a heterogenous
  /// list is really a value of the surrounding map).
  ///
  /// Must only be used for casts which would definitely *succeed*
  
negative.code: /// If applied to a class method, or parameter of such,
  /// any method implementing that interface method is also annotated.
  /// If multiple `Since` annotations apply to the same declaration or
  /// parameter, the latest version takes precedence.
  ///
  /// Any use of a marked API may trigger a warning if the using code
  /// does not require an SDK version guaranteeing that the API is available,
  