title: Finding the first occurrence in 2 lists in Python
body: <p>I'm having trouble doing this, I want to do a function that does this : I have 2 lists : <code>list1 = [8,6,0] and list2 = [6,0]</code>. I want to keep the first value that's the same between the 2 lists (6 here). Like if I had list1 = [a,b,c] and list2 = [b,c]. I'd like to keep only value b. 
  I've already tried this :    </p>
  
  <pre><code>def listFirstValue (list1,list2) :
  for x in list1 :  
    for y in list2 :
      if x == y :
        break
    break
  return a
  </code></pre>
  
  <p>Thank you for your response.</p>