code: function appendUrls(url, arr){
  			var i = arr.length,
  				found = false;
  			while (i--) {
  			    if(arr[i] === url){
  			    	found = true;
  			    	break;
  			    }
  			}
  			if(!found) arr.push(url);
  		 }
docs: appends url if its not already in the array