/**
 * Custom hook to determine if the current viewport matches a specified media query.
 *
 * This hook uses the `window.matchMedia` API to evaluate the media query and listens for changes
 * to dynamically update the result when the viewport changes.
 *
 * @param {string} query - A valid media query string (e.g., "(max-width: 768px)").
 * @returns {boolean} - A boolean value indicating whether the current viewport matches the media query.
 *
 * @example
 * // Check if the viewport is mobile-sized
 * const isMobile = useMediaQuery("(max-width: 768px)");
 *
 * if (isMobile) {
 *   console.log("The viewport is mobile-sized.");
 * } else {
 *   console.log("The viewport is not mobile-sized.");
 * }
 */
export declare const useIsMediaQuery: (query: string) => boolean;