anchor.diff:  external T unsafeCast<T>(dynamic value);
   
   // Powers of 10 up to 10^22 are representable as doubles.
  -// Powers of 10 above that are only approximate due to lack of precission.
  +// Powers of 10 above that are only approximate due to lack of precision.
   // Used by double-parsing.
   const POWERS_OF_TEN = const [
     1.0, // 0
  
positive.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 precendence.
  ///
  /// 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,
  
negative.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 heterogeneous
  /// list is really a value of the surrounding map).
  ///
  /// Must only be used for casts which would definitely *succeed*
  