[Twisted-Python] Closing a connection?

[Britt Green]

I know this answer is obvious, but I can't seem to find it. How do I
close a connection? I have this bit of code:

class Echo(basic.LineReceiver):
    
    def lineReceived(self, data):
        "As soon as any data is received, write it back."

        if data == "quit":
            self.transport.write("Quit command received.\r\n")

How do I kill the client's connection? I've checked the docs and
Google, but couldn't find a thing on it. I know its something totally
obvious that I'm overlooking though...

Britt