title: Check if discrete signal is periodic (or close to), given discrete event times
body: <p>So I have a list of times Z (see below) when a particular event happens. How can I see how close to periodic is this signal?
  I guess, I can find the pairwise time differences between serial events and see if it's an approximately steady quantity, but is there a pythonic way to do this?</p>
  
  <pre><code>Z = [7.72, 10.9, 13.9, 16.69, 19.5, 22.31, 25.0, 27.69...]
  </code></pre>