UNITY3D rotate object script

/*
    Copyright 2013, Aleksander Hristov, boxcollider@gmail.com .

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/


using UnityEngine;
using System.Collections;


//Class responsible for rotating an object along Y world axys.
//Attach this script to an empty game object in scene.


public class GameObjectRotator : MonoBehaviour {
  Transform myTransform;
  public float rotationSpeed=10f;

 void Start () {
   myTransform=transform;
 } 

 void Update () {
    myTransform.Rotate(Vector3.up*rotationSpeed*Time.deltaTime,Space.World);
 }
 
    void OnBecameVisible() {
        enabled = true;
    }
 
    void OnBecameInvisible() {
        enabled = false;
    } 
}