title: How to remove a trailing comma?
body: <p>Given strings like:</p>
  
  <pre><code>Bob
  Bob,
  Bob
  Bob Burns,
  </code></pre>
  
  <p>How can you return that w/o a comma?</p>
  
  <pre><code>Bob
  Bob
  Bob
  Bob Burns
  </code></pre>
  
  <p>Also, I would want this method not to break if passed a nil, just to return a nil?</p>
  
  <pre><code>def remove_trailing_comma(str)
    !str.nil? ? str.replace(",") :nil
  end
  </code></pre>