/**
 * Internal class that tracks state for the external `iterate` function.
 */
export declare class Iterator {
    /**
     * Stores Errors as we encounter them to avoid duplication.
     */
    seenErrors: Set<Error>;
    /**
     * Constructs an Iterator.
     */
    constructor();
    /**
     * Implements the external `iterate` function, using its instance to track
     * state and avoid duplicate references.
     * @param err - Error instance to iterate.
     */
    iterate(err: Error): IterableIterator<Error>;
}