in src/session/stream.rs [230:239]
fn deregister(&mut self, registry: &mio::Registry) -> std::result::Result<(), std::io::Error> {
if let Some(stream) = &mut self.inner {
stream.deregister(registry)
} else {
Err(Error::new(
ErrorKind::NotConnected,
"session is not connected",
))
}
}