sanitize_term

/**
 * Check if a term is an ancestor of another term.
 *
 * You can use either an ID or the term object for both parameters.
 *
 * @since 3.4.0
 *
 * @param int|object $term1    ID or object to check if this is the parent term.
 * @param int|object $term2    The child term.
 * @param string     $taxonomy Taxonomy name that $term1 and `$term2` belong to.
 * @return bool Whether `$term2` is a child of `$term1`.
 */
function term_is_ancestor_of( $term1, $term2, $taxonomy ) {
	if ( ! isset( $term1->term_id ) ) {
		$term1 = get_term( $term1, $taxonomy );
	}
	if ( ! isset( $term2->parent ) ) {
		$term2 = get_term( $term2, $taxonomy );
	}

	if ( empty( $term1->term_id ) || empty( $term2->parent ) ) {
		return false;
	}
	if ( $term2->parent === $term1->term_id ) {
		return true;
	}