import Span from './span';
import { SpanManager } from './span_manager';
/**
 * ScopeManger using Node.js {@link async_hooks|https://nodejs.org/api/async_hooks.html}
 */
export declare class AsyncHookSpanManager implements SpanManager {
    readonly _spans: Map<number, Span>;
    private readonly _hook;
    active(): Span | null;
    activate<A>(span: Span | null, f: () => A): A;
}