Function markFunction

docs/2.2/js/jquery.js:1316–1319

* Mark a function for special use by Sizzle * @param {Function} fn The function to mark

( fn )

 * @param {Function} fn The function to mark
 */
function markFunction( fn ) {
    fn[ expando ] = true;
    return fn;
}

/**
 * Support testing using an element