[Twisted-Python] How do I know the server from reactor.listenTCP already started listening?

[David Kao]

When the call to listenTCP returns, is the server actively waiting for
TCP connections?

Let's say reactor.run() has been called. Can I do the following back-to-back?

reactor.listenTCP(4321, serverfactory)
reactor.connectTCP("localhost", 4321, clientfactory)

Basically, I am almost starting a server and a client back-to-back
that connects to each other. I would like to know if the server is in
"listening" state before my client attempts to connect.

Thanks.

David Kao