/**
 * Produces the intermediate accumulator values of a reduction over the source iterable.
 *
 * @typeParam T - Element type produced by the source iterable.
 * @typeParam TOut - Accumulator result type when a distinct seed is supplied.
 * @typeParam TT - Effective accumulator type when `seed` is optional.
 * @param src - Source iterable providing values for the running aggregation.
 * @param aggFunc - Combiner invoked with the previous accumulator, current element, and current index.
 * @param seed - Optional initial accumulator; falls back to the first element when omitted.
 * @returns A deferred iterable yielding each intermediate accumulator value in evaluation order.
 * @throws {Error} If `seed` is omitted and the source iterable is empty.
 * @example
 * ```ts
 * const runningTotals = [..._scan([1, 2, 3], (prev, curr) => prev + curr, 0)];
 * console.log(runningTotals); // [1, 3, 6]
 * ```
 */
export declare function _scan<T, TOut>(src: Iterable<T>, aggFunc: (prev: TOut, curr: T, idx: number) => TOut, seed: TOut): Iterable<TOut>;
export declare function _scan<T, _>(src: Iterable<T>, aggFunc: (prev: T, curr: T, idx: number) => T): Iterable<T>;
/**
 * Curried version of {@link _scan}.
 */
export declare function scan<T, TOut>(aggFunc: (prev: TOut, curr: T, idx: number) => TOut, seed: TOut): (source: Iterable<T>) => Iterable<TOut>;
export declare function scan<T>(aggFunc: (prev: T, curr: T, idx: number) => T): (source: Iterable<T>) => Iterable<T>;