code: function keymage(scope, keychain, fn, options) {
          var args = parsed(scope, keychain, fn, options);
          fn = args[2];
          options = args[3];
          fn._keymage = options || {};
          fn._keymage.original = keychain;
          assignKey.apply(null, args);
  
          return function () {
              unassignKey.apply(null, args);
          };
      }
docs: optional arguments: scope, options.