KeyboardDirectionalKeys constructor
      
      KeyboardDirectionalKeys({ 
    
    
- required LogicalKeyboardKey up,
 - required LogicalKeyboardKey down,
 - required LogicalKeyboardKey left,
 - required LogicalKeyboardKey right,
 
Implementation
KeyboardDirectionalKeys({
  required this.up,
  required this.down,
  required this.left,
  required this.right,
});