$args =
{
 message_type => MQTT_PINGREQ,
 remaining => 'HELLOWORLD',
}

c0 0a 48 45  4c 4c 4f 57    4f 52 4c 44

PingReq/at-most-once 
  48 45 4c 4c 4f 57 4f 52 4c 44                    HELLOWORLD