How to use the pouchdb-wrappers.installWrapperMethods function in pouchdb-wrappers

return utils.nodify(Promise.resolve().then(function () {
    // add wrappers and make system db
    if (!info.isOnlineAuthDB) {
      wrappers.installWrapperMethods(args.db, writeWrappers);
      systemDB.installSystemDBProtection(args.db);

      // store validation doc
      return args.db.put(designDoc);
    }
  }).catch(function (err) {
    /* istanbul ignore if */

app.dbWrapper.registerWrapper(function (name, db, next) {
    // db.info() should just return the non-uri encoded db name
    wrappers.installWrapperMethods(db, {
      info: function (orig) {
        return orig().then(function (info) {
          info.db_name = decodeURIComponent(info.db_name);
          return info;
        });
      }
    });

    return next();
  });

return origOn.apply(changes, [event, function (res) {
          listener(modifyChanges(res));
        }]);
      }
      return origOn.apply(changes, [event, listener]);
    };

    var origThen = changes.then;
    changes.then = function (resolve, reject) {
      return origThen.apply(changes, [function (res) {
        resolve(modifyChanges(res));
      }, reject]);
    };
    return changes;
  };
  wrappers.installWrapperMethods(db, handlers);
};

});
          });
        }]);
      }
      return origOn.apply(changes, [event, listener]);
    };

    var origThen = changes.then;
    changes.then = function (resolve, reject) {
      return origThen.apply(changes, [function (res) {
        modifyChanges(res).then(resolve, reject);
      }, reject]);
    };
    return changes;
  };
  wrappers.installWrapperMethods(db, handlers);
};

});
          });
        }]);
      }
      return origOn.apply(changes, [event, listener]);
    };

    var origThen = changes.then;
    changes.then = function (resolve, reject) {
      return origThen.apply(changes, [function (res) {
        return modifyChanges(res).then(resolve, reject);
      }, reject]);
    };
    return changes;
  };
  wrappers.installWrapperMethods(db, handlers);
};

app.dbWrapper.registerWrapper(function (name, db, next) {
    //'fix' the PouchDB api (support opts arg everywhere)
    function noop(orig) {
      return orig();
    }
    var wrapperMethods = {};
    ['info', 'removeAttachment'].forEach(function (name) {
      wrapperMethods[name] = noop;
    });
    wrappers.installWrapperMethods(db, wrapperMethods);
    return next();
  });