title: Check if something is a list
body: <p>What is the easiest way to check if something is a list?</p>
  
  <p>A method <code>doSomething</code> has the parameters <code>a</code> and <code>b</code>. In the method, it will loop through the list <code>a</code> and do something. I'd like a way to make sure <code>a</code> is a <code>list</code>, before looping through - thus avoiding an error or the unfortunate circumstance of passing in a string then getting back a letter from each loop.</p>
  
  <p>This question must have been asked before - however my googles failed me. Cheers.</p>