If methods can be called asynchronously, the client handler is not safe to use because there's no lock being taken to prevent mixing up the messages to drain from the socket.
So what can happen is that if you call two methods at the same time, _next_message() can drain 2 messages in the wrong order in one of the call handler.
This result in method calls spuriously having the wrong outputs because a {"continues": false} will be interpreted as a {}.
If methods can be called asynchronously, the client handler is not safe to use because there's no lock being taken to prevent mixing up the messages to drain from the socket.
So what can happen is that if you call two methods at the same time,
_next_message()can drain 2 messages in the wrong order in one of the call handler.This result in method calls spuriously having the wrong outputs because a
{"continues": false}will be interpreted as a{}.