/**
 * Returns the value of the given attribute closest to the given element (including itself)
 *
 * @internal
 * @param {Element} $element - The element to start walking the DOM tree up
 * @param {string} attributeName - The name of the attribute
 * @returns {string | null} Attribute value
 */
export function closestAttributeValue(
    $element: Element,
    attributeName: string,
): string | null;