title: Binary operator '==' cannot be applied to two 'Equatable' operands... what?
body: <p>You can see in the image below that I was trying to extend the <code>Collection</code> protocol to include a method called <code>removingDuplicates</code>, which is supposed to do exactly what it says. The error that the compiler is displaying seems to directly contradict the definition of the <code>Equatable</code> protocol. Is this a bug or am I misunderstanding something?</p>
  
  <p><a href="https://i.stack.imgur.com/ixyin.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ixyin.png" alt="enter image description here"></a></p>