Smooth door open C#

using System.Collections;
using UnityEngine;

public class Door : MonoBehaviour
{
    //Make an empty game object and call it "Door"
    //Rename your 3D door model to "Body"
    //Parent a "Body" object to "Door"
    //Make sure thet a "Door" object is in left down corner of "Body" object. The place where a Door Hinge need be
    //Add a box collider to "Door" object and make it much bigger then the "Body" model, mark it trigger
    //Assign this script to a "Door" game object that have box collider with trigger enabled
    //Press "f" to open the door and "g" to close the door
    //Make sure the main character is tagged "player"

    public float smooth = 2.0f;
    public float openAngle = 90.0f;

    private bool open;
    private bool inSight;
    private Vector3 defaultRot;
    private Vector3 openRot;
    private Transform mTransform;
    private Transform cachedTransform { get { if (!mTransform) mTransform = transform; return mTransform; } }

    void OnEnable()
    {
        defaultRot = cachedTransform.eulerAngles;
        openRot = new Vector3(defaultRot.x, defaultRot.y + openAngle, defaultRot.z);
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.E) && inSight) {
            open = !open;
        }

        Vector3 target = open ? openRot : defaultRot;
        cachedTransform.eulerAngles = Vector3.Slerp(cachedTransform.eulerAngles, target, Time.deltaTime * smooth);
    }

    void OnGUI()
    {
        if (inSight) {
            GUI.Label(new Rect(Screen.width / 2 - 75, Screen.height - 100, 150, 30), "Press 'F' to open the door");
        }
    }

    void OnTriggerEnter(Collider other)
    {
        if (other.gameObject.tag == "Player") {
            inSight = true;
        }
    }
    void OnTriggerExit(Collider other)
    {
        if (other.gameObject.tag == "Player") {
            inSight = false;
        }
    }
}