import type { IMessage } from './IMessage.ts';
import type { IMessageMeta } from './IMessageMeta.ts';
export interface IMessageHandler {
    (message: IMessage, meta?: IMessageMeta): unknown | Promise<unknown>;
}
export interface IObservable {
    /**
     * Setup a listener for a specific event type
     */
    on(type: string, handler: IMessageHandler): void;
    /**
     * Remove previously installed listener
     */
    off(type: string, handler: IMessageHandler): void;
}
export declare const isObservable: (obj: unknown) => obj is IObservable;