title: Split list in tuples of three
body: <p>I have a list</p>
  
  <pre><code>L = [1, 2, 3, 4...]
  </code></pre>
  
  <p>which have <code>n*3</code> elements. I want to be able to do something like</p>
  
  <pre><code>for a, b, c in three_tuple_split(L)
  </code></pre>
  
  <p>in a pythonic way but can't come up with one.</p>