/**
 * Is a given value a function
 *
 * @param o
 * @returns {boolean}
 */
export declare function isFunction(o: any): o is Function;
/**
 * is string
 *
 * @param o
 * @returns {boolean}
 */
export declare function isString(o: any): o is String;
export declare function isPromise(o: any): o is Promise<any>;
/**
 * Is array type guard
 *
 * @param o
 */
export declare function isArray<T>(o: any | Array<T>): o is Array<T>;