title: Converting a List<int> to a comma separated string
body: <p>Is there a way to take a List and convert it into a comma separated string?  </p>
  
  <p>I know I can just loop and build it, but somehow I think some of you guys a more cool way of doing it?</p>
  
  <p>I really want to learn these types of 'tricks', so please explain or link to the docs on the method you use.</p>