title: finding duplicate elemntes in a list with LISP language
body: <p>I'm new Lisp programmer and need some help<br>
  I want to write a function that find duplicate elements in a list but i cant write it.<br>
  I need something like this in lisp:</p>
  
  <pre><code>for(int i=0; i &lt; myList.length(); i++)  
     for(int j=i+1; j &lt; myList.Length(); j++)
     {  
        if(myList[i] == myList[j])  
           cout &lt;&lt; myList[i] &lt;&lt; endl;
     }
  </code></pre>
  
  <p>Anybody can help me?</p>