pub trait Message: Clone + Debug + Default + PartialEq + RosMsg + Send + Sync + 'static {
// Required methods
fn msg_definition() -> String;
fn md5sum() -> String;
fn msg_type() -> String;
// Provided method
fn set_header(&mut self, _clock: &Arc<dyn Clock>, _seq: &Arc<AtomicUsize>) { ... }
}