title: Checking number of elements in Python's `Counter`
body: <p>Python 2.7/3.1 introduced the awesome <code>collections.Counter</code>.</p>
  
  <p>My question: How do I count how many "element appearances" a counter has?</p>
  
  <p>I want this:</p>
  
  <pre><code>len(list(counter.elements()))
  </code></pre>
  
  <p>But shorter.</p>