I want to use the tracking function. but when I coding with 'ITrackableEventHandler', an error occurs(Error CS0246 : The type or namespace name 'type/namespace' could not be found). The version I am using is Unity 2020.3 and Vuforia 10.5.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Vuforia;

public class csTracking : MonoBehaviour, ITrackableEventHandler
{
    private TrackableBehaviour mTrackableBehaviour;
    // Start is called before the first frame update
    void Start()
    {
        mTrackableBehaviour = GetComponent<TrackableBehaviour>();
        if(mTrackableBehaviour)
        {
            mTrackableBehaviour.RegisterTrackableEventHandler(this);
        }
    }

    // Update is called once per frame
    void Update()
    {
        
    }
}

I searched, but I couldn't find a replacement code.