title: Wildcard pattern (or _ argument) with no argument
body: <p>I am confused as to the changeFloor(_:) arguments, in which the wildcard _ is specified and assigned to nothing. Doesn't this go against the entire purpose of the wild-card, which is to not have to re-type the parameter names? In addition, why is the wild-card variable being assigned to nothing when it should be the variable "controls" of type UISegmentedControl() being passed in in order for the action to access it. </p>
  
  <pre><code>@objc func changeFloor(_ controls: UISegmentedControl){
              switch controls.selectedSegmentIndex {
              case 0:
                  print("hi")
              case 1:
                  print("bye!")
              default:
                  print("no item found!")
              }
          }
  
  controls.addTarget(self, action: #selector(changeFloor(_:)), for: .valueChanged)
  </code></pre>