[VR] VIVE controller press to load scene

Hey all, so I have a small issue. I have a sort of "death screen" and would like when the user presses the trigger on either VIVE controller it will load a scene, for now we will just call it "Intro". I have this script already but keep getting messages that the "controller"does not exist in the context. I am very very new to coding in terms of Virtual Reality and have no idea what the actual "key" name is for the trigger on the VIVE controller. If anyone could help me fix my script it would be much appreciated!

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 using Valve.VR;
 
 public class DeathLoad : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         if (controller.GetPress(TriggerButton))
         {
             controller.TriggerHapticPulse(1000);
             SceneManager.LoadScene("Intro");
         }
 
     }
 }