/** An op refused: a code the client can test (bad_request, not_found, conflict, …) and words for a person. */
export declare class OpError extends Error {
    code: string;
    constructor(code: string, message: string);
}
export declare function str(v: unknown): v is string;
/** The path with links resolved; the path itself when it cannot be. */
export declare function realPath(p: string): string;
/** Text from an op's argument: control characters as spaces, trimmed, at most `max`. */
export declare const taskText: (v: unknown, max: number) => string;