code: function popCallbackFromArgs(args) {                                                                                  // 764
    // Pull off any callback (or perhaps a 'callback' variable that was passed                                          //
    // in undefined, like how 'upsert' does it).                                                                        //
    if (args.length && (args[args.length - 1] === undefined || args[args.length - 1] instanceof Function)) {            // 767
      return args.pop();                                                                                                // 770
    }                                                                                                                   // 771
  }
docs: 762