import type { ConfigInput } from './config';
import { HarborClient } from './module';
/**
 * Verify if a harbor client singleton instance exists.
 *
 * @param key
 */
export declare function hasClient(key?: string): boolean;
/**
 * Set the harbor client singleton instance.
 *
 * @param client
 * @param key
 */
export declare function setClient(client: HarborClient, key?: string): HarborClient;
/**
 * Receive a harbor singleton instance.
 *
 * @param key
 */
export declare function useClient(key?: string): HarborClient;
/**
 * Unset a harbor client singleton instance.
 *
 * @param key
 */
export declare function unsetClient(key?: string): void;
/**
 * Create a harbor client.
 *
 * @param input
 */
export declare function createClient(input?: ConfigInput): HarborClient;
/**
 * Check if the argument is of instance Client.
 *
 * @param input
 */
export declare function isClient(input: unknown): input is HarborClient;