/**
  * @param Song $song
  * @param Request $request instance of Method Injection
  * @return \Illuminate\Http\RedirectResponse|\Illuminate\Routing\Redirector
  */
 public function update(Song $song, Request $request)
 {
     //Set all properties at once (must be mass assignable)
     $song->fill(['title' => $request->input('title'), 'lyrics' => $request->input('lyrics')]);
     //        $song->fill($request);
     //Set properties individually
     //        $song->title    = $request->input('title');
     //        $song->lyrics   = $request->input('lyrics');
     $song->save();
     return redirect('songs/' . $song->slug);
 }