/**
  * Display the information for machine $id
  *
  * @param string $id
  * @return \Illuminate\Http\Response
  */
 public function show($id)
 {
     // Retrieve details for a specific machine
     $machine = Machine::findOrFail($id);
     // application will return HTTP 404 if $id doesn't exist
     // Retrieve the active tubes for machine $id
     $tubes = $this->getTubes($id);
     // Retrieve the surveys for machine $id
     $surveys = TestDate::where('machine_id', $id)->orderBy('test_date', 'asc')->get();
     // Retrieve the operational notes for machine $id
     $opNotes = $this->getOperationalNotes($id);
     return view('machine.detail', ['machine' => $machine, 'tubes' => $tubes, 'opnotes' => $opNotes, 'surveys' => $surveys]);
 }