/**
 * @license
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { Auth, UserCredential } from '../../model/public_types';
/**
 * Asynchronously signs in as an anonymous user.
 *
 * @remarks
 * If there is already an anonymous user signed in, that user will be returned; otherwise, a
 * new anonymous user identity will be created and returned.
 *
 * This method is not supported by {@link Auth} instances created with a
 * {@link @firebase/app#FirebaseServerApp}.
 *
 * @param auth - The {@link Auth} instance.
 *
 * @public
 */
export declare function signInAnonymously(auth: Auth): Promise<UserCredential>;