Trouble using WWW.LoadImageIntoTexture

Hi, I'm trying to download a picture from a URL and show it on a Panel. I came across this official script from Unity. I copied it dry and tried compiling it.

 using UnityEngine;
 using System.Collections;
 
 public class test : MonoBehaviour {
 
     var url = "http://images.earthcam.com/ec_metros/ourcams/fridays.jpg";
     // Use this for initialization
     void Start () {
         
 
 
             // Create a texture in DXT1 format
             renderer.material.mainTexture = new Texture2D(4, 4, TextureFormat.DXT1, false);
             while(true) {
                 // Start a download of the given URL
                 
             var www = new WWW(url);
 
                 // wait until the download is done
                 yield www;
 
                 // assign the downloaded image to the main texture of the object
                 www.LoadImageIntoTexture(renderer.material.mainTexture);
             }
         }
 
 
     
     // Update is called once per frame
     void Update () {
     
     }
 }

I get the error "A local variable named 'www' is already defined in this scope". I can't seem to figure it out why. Any ideas? Thanks