/**
 * It register the alpha extension to the Faker instance.
 *
 * @param fake Faker instance
 *
 * @example
 * ```ts
 * import fake from '@micra/faker';
 * import {alpha} from '@micra/faker/extensions/date';
 *
 * fake.extend({alpha});
 * ```
 */
export declare function alpha(fake: Faker.Instance): (length?: number) => string;