error CS0246: The type or namespace name 'EditModeInputHandler' could not be found (are you missing a using directive or an assembly reference?)

$$anonymous$$ I am following a turoial to make start menu scene and having t$$anonymous$$s error-

error CS0246: The type or namespace name 'EditModeInputHandler' could not be found (are you missing a using directive or an assembly reference?)

from t$$anonymous$$s location: Library\PackageCache\com.unity.timeline@1.2.18\Editor\Manipulators\EditMode.cs(77,16)

these codes are not written by me I t$$anonymous$$nk it is build in unity script :

 public static EditModeInputHandler inputHandler
         {
             get { return s_InputHandler; }
         }
 

AND

     static ITrimmable s_CurrentTrimItem;
     static TrimEdge s_CurrentTrimDirection;
     static MoveItemHandler s_CurrentMoveItemHandler;
     static EditModeInputHandler s_InputHandler = new EditModeInputHandler();

These scripts show error in the place of EditModeInputHandler i don't know what to do please help and here is the error image :

Code error 1: