title: Converting a list of tuples into a dict
body: <p>I have a list of tuples like this:</p>
  
  <pre><code>[
  ('a', 1),
  ('a', 2),
  ('a', 3),
  ('b', 1),
  ('b', 2),
  ('c', 1),
  ]
  </code></pre>
  
  <p>I want to iterate through this keying by the first item, so, for example, I could print something like this:</p>
  
  <pre><code>a 1 2 3
  b 1 2
  c 1
  </code></pre>
  
  <p>How would I go about doing this without keeping an item to track whether the first item is the same as I loop around the tuples? This feels rather messy (plus I have to sort the list to start with)...</p>