title: remove duplicated lists inside list in lisp
body: <p>How do i remove duplicated lists inside a list in common-lisp?
  I tried this:</p>
  
  <pre><code>(remove-duplicates '( (1 2 3) (1 2 3)))                           
  </code></pre>
  
  <p>But it evaluates to  <code>((1 2 3) (1 2 3))</code>, not <code>((1 2 3))</code>.</p>
  
  <p>Thanks.</p>