export declare function formatDoc(content?: string): string;
export declare function groupByArray<T>(array: T[], key: (value: T) => string): T[][];
export declare function concatWith({ prefix, joiner, suffix, defaultValue }: {
    prefix?: string;
    joiner?: string;
    suffix?: string;
    defaultValue?: string;
}, ...items: (string | undefined | null)[]): string;