def add_service(self, service):
if service.protocol in self._services:<EOL><INDENT>existing = self._services[service.protocol]<EOL>if not existing.superseeded_by(service):<EOL><INDENT>return<EOL><DEDENT><DEDENT>self._services[service.protocol] = service<EOL>
Add a new service.

        If the service already exists, it will be replaced.