what should be filled up so the code can run successfully? : <pre><code>import java.util.*;   

public class Main
{
  public static void main(String[] args) 
  {
      List student = new ArrayList();
      student.add("123");
      student.add("ABC");
      student.add("70.8");    

      Iterator itr = listItr.iterator();

      while(itr.hasNext())      
      {
          System.out.println(itr.next()); 

      }
 }  
</code></pre>

<p>}
  What should i write here Iterator itr = _________; in order to get an 
  output? </p>
