anchor.diff:  
     /// Returns a [Reference] to [symbol] with [url].
     ///
  -  /// This function overrides [code_builder.refer] so as to ensure that [url] is
  +  /// This function overrides `code_builder.refer` so as to ensure that [url] is
     /// given.
     static Reference referImported(String symbol, String? url) =>
         Reference(symbol, url);
  
positive.code:     if (this is ClassElement) {
        return "The class '$name'";
      } else if (this is MethodElement) {
        var className = enclosingElement!.name;
        return "The method '$className.$name'";
      } else if (this is PropertyAccessorElement) {
        var className = enclosingElement!.name;
        return "The property accessor '$className.$name'";
      } else {
        return 'unknown element';
  
negative.code:   ///
    /// If any type in the above positions is private, [function] is un-stubbable.
    /// If the return type is potentially non-nullable, [function] is
    /// un-stubbable, unless [isParameter] is true (indicating that [function] is
    /// found in a parameter of a method-to-be-stubbed) or
    /// [allowUnsupportedMember] is true, or [hasDummyGenerator] is true
    /// (indicating that a dummy generator, which can return dummy values, has
    /// been provided).
    List<String> _checkFunction(
  