/**
 * @license
 * Copyright 2017 Google Inc.
 *
 * 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.
 */
/**
 * Unconditionally fails, throwing an Error with the given message.
 *
 * Returns any so it can be used in expressions:
 * @example
 * let futureVar = fail('not implemented yet');
 */
export declare function fail(failure: string): never;
/**
 * Fails if the given assertion condition is false, throwing an Error with the
 * given message if it did.
 */
export declare function assert(assertion: boolean, message: string): asserts assertion;