w.size_hint(self.flags.len() + 2);
(self.flags.len() as u16).write(w)?;
for f in self.flags.iter().rev() { // Swap back to big-endian
w.size_hint(self.flags.len() + 2);
(self.flags.len() as u16).write(w)?;
for f in self.flags.iter().rev() { // Swap back to big-endian