Return ``True`` if this connection is closing.

        The connection is considered closing if either side has
        initiated its closing handshake or if the stream has been
        shut down uncleanly.

def is_closing(self) -> bool:
        """Return ``True`` if this connection is closing.

        The connection is considered closing if either side has
        initiated its closing handshake or if the stream has been
        shut down uncleanly.
        """
        return self.stream.closed() or self.client_terminated or self.server_terminated