anchor.diff:      _kDecreaseIndex: decrease,
       _kShowOnScreen: showOnScreen,
       _kMoveCursorForwardByCharacter: moveCursorForwardByCharacter,
  -    _kMoveCursorBackwardByCharacter: moveCursorBackardByCharacter,
  +    _kMoveCursorBackwardByCharacter: moveCursorBackwardByCharacter,
     };
   
     @override
  
positive.code:       case _kMoveCursorForwardByCharacter:
          return 'SemanticsAction.moveCursorForwardByCharacter';
        case _kMoveCursorBackwardByCharacter:
          return 'SemanticsAction.moveCursorBackardByCharacter';
      }
      return null;
    }
  
negative.code:   /// Move the cursor backward by one character.
    ///
    /// This is for example used by the cursor control in text fields.
    static const SemanticsAction moveCursorBackwardByCharacter = const SemanticsAction._(_kMoveCursorBackwardByCharacter);
  
    /// The possible semantics actions.
    ///
  