title: Cases where use of tuple is a must
body: <p>In Python, the only difference between a list and a tuple that I know of is <strong>"lists are mutable but tuples are not"</strong>. But as far as I believe, it depends on whether the coder wants to risk mutability or not.</p>
  
  <p>So I was wondering whether there are any cases where the use of a tuple over a list is a must. Things that can not be done with a list but can be done with a tuple?</p>