anchor.diff:  
       return body;
     }
  +
  +  @override
  +  void onMount() {
  +    super.onMount();
  +
  +    gameRef.ready().whenComplete(
  +          () => body.joints.whereType<_FlipperJoint>().first.unlock(),
  +        );
  +  }
   }
   
   class _FlipperSpriteComponent extends SpriteComponent with HasGameRef {
  
positive.code:   /// The joint is locked when initialized in order to force the [Flipper]
    /// at its resting position.
    void lock() {
      const angle = _halfSweepingAngle;
      setLimits(
        angle * side.direction,
        angle * side.direction,
      );
    }
  
    /// Unlocks the [Flipper] from its resting position.
  
negative.code:     );
      final joint = _FlipperJoint(jointDef);
      world.createJoint(joint);
    }
  
    List<FixtureDef> _createFixtureDefs() {
  