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

hi I am following a turoial to make start menu scene and having this error-

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

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

these codes are not written by me I think 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:

please help me !!! by reply or only upvote i need help