/**
 * Checks if a string contains only numberical characters.
 * An optional flag in config can be used to allow commas.
 * @param {*} value The value to check for only numerical characters.
 * @param {object} config The config of the validation check.
 * @returns true if value passes the regex, false if not.
 */
declare const mustBeNumbersOnly: (value: any, config: any) => boolean;
export default mustBeNumbersOnly;