Inheritance: extends Illuminate\Foundation\Http\FormRequest
 public function postContactUs(ContactUsRequest $request)
 {
     if (Auth::check()) {
         $user = Auth::user();
     }
     $request->merge(['full_name' => $user->full_name, 'email' => $user->email]);
     Mail::to($user->email)->send(new ContactUsMail($request->all()));
     return redirect()->back();
 }