declare global {
    interface Promise<T> {
        /**
         * Delay between the promise chain.
         *
         * @param {number} millisecond
         * - a time for the delay
         *
         * @return {Promise<T>}
         * A value which pass through within a promise
         *
         * @example
         * Promise.resolve('a')
         *   .delay(300)
         *   .then(doSomething)
         * // return 'a' in a promise after delay 300 ms
         */
        delay(millisecond: number): Promise<T>;
    }
}
export {};