title: Find matching values in a list of lists
body: <p>I'm trying to iterate over a list of lists in python 2.7.5 and return those where the first value is found in a second list, something like this:</p>
  
  <pre><code>#python 2.7.5
  list1 = ['aa', 'ab', 'bb', 'bc', 'cc']
  list2 = [['aa', 1, 3, 7],['de', 2, 2, 1],['bc', 3, 4, 4]]
  
  list3 = []
  for x in list1:
      for y in list2:
          if x == y:
              list3.append(y)
  </code></pre>
  
  <p>So I would want list3 to contain <code>[['aa',1,3,7],['bc', 3, 4, 4]]</code> but instead I just get the whole of list2.</p>