title: Python `dict` indexed by tuple: Getting a slice of the pie
body: <p>Let's say I have </p>
  
  <pre><code>my_dict = {
    ("airport", "London"): "Heathrow",
    ("airport", "Tokyo"): "Narita",
    ("hipsters", "London"): "Soho"
  }
  </code></pre>
  
  <p>What is an efficient (no scanning of all keys), yet elegant way to get all airports out of this dictionary, i.e. expected output <code>["Heathrow", "Narita"]</code>. In databases that can index by tuples, it's usually possible to do something like </p>
  
  <pre><code>airports = my_dict.get(("airport",*))
  </code></pre>
  
  <p>(but usually only with the 'stars' sitting at the rightmost places in the tuple since the index usually is only stored in one order).</p>
  
  <p>Since I imagine Python to index dictionary with tuple keys in a similar way (using the keys's inherent order), I imagine there might be a method I could use to slice the index this way?</p>
  
  <p>Edit1: Added expected output</p>
  
  <p>Edit2: Removed last phrase. Added '(no scanning of all keys)' to the conditions to make it clearer.</p>