title: Type of "Int -> Bool" ,"Int-> Bool -> Int","Int-> String -> Int－> Bool"
body: <p>There is a func: </p>
  
  <pre><code> func (first: Int) -&gt; Int -&gt; Bool -&gt; String {
  
      return  ?
   }
  </code></pre>
  
  <p>How to write the return value?
  I'm so confused about the return type like of the func above.</p>