import { OperatorAsyncFunction } from '../../interfaces';
export declare function scan<T, R = T>(accumulator: (previousValue: R, currentValue: T, currentIndex: number) => R | Promise<R>, seed?: never[]): OperatorAsyncFunction<T, R>;
export declare function scan<T, R = T>(accumulator: (previousValue: R, currentValue: T, currentIndex: number) => R | Promise<R>, seed?: R): OperatorAsyncFunction<T, R>;