/**
  * Display a listing of the resource.
  *
  * @return \Illuminate\Http\Response
  */
 public function index(Request $request)
 {
     //view for admin, only read: agent and developer,
     $tracings = Tracing::filter($request->get('date'), $request->get('state'), $request->get('phase'));
     return view('tracings/list', compact('tracings'));
 }