title: Most Pythonic and efficient way to insert character at end of string if not already there
body: <p>I have a string:</p>
  
  <pre><code>b = 'week'
  </code></pre>
  
  <p>I want to check if the last character is an "s". If not, append an "s".</p>
  
  <p>Is there a Pythonic one-liner for this one?</p>