/**
 * Validates a Brazilian PIS (Programa de Integração Social) number.
 *
 * @param {string} pis - The PIS number to validate.
 * @returns {boolean} True if the PIS number is valid, false otherwise.
 *
 * @example
 * ```typescript
 * isValidPis("120.56874.10-7"); // true
 * isValidPis("12056874107"); // true
 * isValidPis("00000000000"); // false (reserved number)
 * ```
 */
export declare const isValidPis: (pis: string) => boolean;