def handle(self, *layers: BaseLayer):
self.sent = []<EOL>stack = Stack(list(layers))<EOL>message = TestMessage(stack)<EOL>responder = TestResponder(self)<EOL>run(self._notify(message, responder))<EOL>
Call this method to send a test message. Call it OUTSIDE the async
loop. It will return when the message is fully handled.