Source

File: wp-includes/functions.php

function wp_is_uuid( $uuid, $version = null ) {

	if ( ! is_string( $uuid ) ) {
		return false;
	}

	if ( is_numeric( $version ) ) {
		if ( 4 !== (int) $version ) {
			_doing_it_wrong( __FUNCTION__, __( 'Only UUID V4 is supported at this time.' ), '4.9.0' );
			return false;
		}
		$regex = '/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/';
	} else {
		$regex = '/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/';
	}

	return (bool) preg_match( $regex, $uuid );
}