/**
 * @module indicative-rules
 */
/**
 *  Returns true if the `input` is one of the affirmative keywords.
 *  Below is the list of case insensitive keywords except `A`.
 *
 *  - 'yes'
 *  - 'true', treu
 *  - 'y'
 *  - 'ok'
 *  - 'okay'
 *  - 'A'
 *
 * @example
 * ```js
 * const { is } = require('indicative')
 *
 * if (is.affirmative('y')) {
 * }
 * ```
 */
export declare const affirmative: (input: string | boolean) => boolean;