Xbox Controller issue

hmiri

Despite having included using HoloToolkit.Unity.InputModule, VS does not recognize the implementation of IXboxControllerHandler, even though I have downloaded the requirements for it via Enable Xbox Controller Support option of Mixed Reality Toolkit -> Configure -> Project Settings.

The following error initially made the impression that I had to manually implement the methods, which I did (what follows after this error) but it still does not recognize this interface. What am I missing or doing wrong?

error CS0535: XboxControllerHandler does not implement interface member HoloToolkit.Unity.InputModule.IXboxControllerHandler.OnXboxAxisUpdate(HoloToolkit.Unity.InputModule.XboxControllerEventData)

using UnityEngine;
using HoloToolkit.Unity.InputModule;

public class XboxControllerHandler : MonoBehaviour, IXboxControllerHandler
{
    public void OnGamePadDetected(GamePadEventData eventData)
    {
        throw new System.NotImplementedException();
    }
    public void OnGamePadLost(GamePadEventData eventData)
    {
        throw new System.NotImplementedException();
    }
    public void OnXboxAxisUpdate(GamePadEventData eventData)
    {
        throw new System.NotImplementedException();
    }
}