title: Optional`s Equatable in Swift
body: <p>We can compare two Optional variables through</p>
  
  <pre><code>public func ==&lt;T : Equatable&gt;(lhs: T?, rhs: T?) -&gt; Bool
  </code></pre>
  
  <p>But when i compare a <code>String?</code> and a <code>String</code>, it goes into the same function above. Why not:</p>
  
  <pre><code>public func ==&lt;T : Equatable&gt;(lhs: T?, rhs: T) -&gt; Bool
  </code></pre>