/**
 * Hold up a stream until a promise resolves. If it errors,
 * the error will be emitted to the stream.
 *
 * @group Transformers
 * @example
 * ```
 * ----a-------b------|
 *
 * interpose(async () => await setTimeout(50))
 *
 * --------a--------b-|
 * ```
 */
export declare function interpose<T>(promise: Promise<void> | ((chunk: T) => Promise<void>)): TransformStream<T, T>;