title: How to iterate through a dictionary without skipping entries with duplicate keys?
body: <p>The code: </p>
  
  <pre><code>params = {'shift' : 'day',
                  'item_served': 'enchiladas',
                  'item_served': 'sushi',
                  'item_served': 'polenta'}
  
  for key, value in params.items():
      print(key)
      print(value)
  </code></pre>
  
  <p>Currently outputs:</p>
  
  <pre><code>shift
  day
  item_served
  polenta
  </code></pre>
  
  <p>But this is what I'm looking for:</p>
  
  <pre><code>shift
  day
  item_served
  enchiladas
  item_served
  sushi
  item_served
  polenta
  </code></pre>
  
  <p>How do you modify the code so that the entries with duplicate keys but different values are not overwritten?</p>