/**
 * Calculates the modulus 10 check digit for a given string.
 *
 * @param {string} str - The string to calculate the check digit for.
 * @returns {number} The calculated check digit (0-9).
 *
 * @example
 * ```typescript
 * mod10("001900000"); // 9
 * ```
 */
export declare const mod10: (str: string) => number;