Hi,I'm trying to use write and read instead of update and digest as per the doc's recommendations but I can't make it work:function createHmac (b64secret, message) {var hmac = crypto.createHmac('sha512', b64secret);hmac.write(message);return hmac.read();}console.log(createMtGoxHmac(b64secret, new Buffer('Test\0Message')));this returns nullwhere am I doing it wrong?