title: checking to see if same value in two lists
body: <p>I have 2 lists one :</p>
  
  <p><code>[(12,23),(12,45),(12,23),(2,5),(1,2),(2,4),(7,34)]</code> which goes up to around 1000 elements
  and another:</p>
  
  <p><code>[(12,23),(12,45),(12,23),(2,5),(1,2),(2,66),(34,7)]</code> which goes up to around 241 elements.</p>
  
  <p>What I want is to check to see if the lists contain any of the same elements and then put them in a new list.</p>
  
  <p>so the new list becomes </p>
  
  <p><code>[(12,23),(12,45),(12,23),(2,5),(1,2)]</code></p>