title: Swift 3 Array contains vs Set contains
body: <p>Just wanted to know which one would be faster?<br>
  AFAIK <code>Set</code> uses <code>hash</code> so it should be faster to find an element in Set. But in quite a few projects I've seen the usage of the <code>array contains</code> where it could have used <code>contains</code> on <code>Set</code>.</p>