public function show($id)
 {
     $brands = array_add($this->brandRepo->lists(), '', 'Seleccione Laboratorio');
     $types = array_add($this->typeTepo->lists(), '', 'Seleccione Tipo de Producto');
     $presentations = array_add($this->presentationRepo->lists(), '', 'Seleccione PresentaciĆ³n');
     $bill = $this->billRepo->findOrFail($id);
     $cashRegister = $this->cashRegisterRepo->last();
     return view('bills/create', compact('bill', 'brands', 'presentations', 'types', 'cashRegister'));
 }