title: Iterating over two lists one after another
body: <p>I have two lists <code>list1</code> and <code>list2</code> of numbers, and I want to iterate over them with the same instructions. Like this:</p>
  
  <pre><code>for item in list1:
    print(item.amount)
    print(item.total_amount)
  
  for item in list2:
    print(item.amount)
    print(item.total_amount)
  </code></pre>
  
  <p>But that feels redundant. I know I can write <code>for item in list1 + list2:</code>, but it has a price of running-time.</p>
  
  <p>Is there a way do that without loose time?</p>