human
Solve the following python programming problem given the following code:
@ defer.inlineCallbacks 
def test_authentication_required_without_tls(self) : 
    processor = FakeProcessor () 
    processor_dependency = dependencies.InstanceDependency (processor) 
    processor_dependency.is_ready = True 
    self.runtime_environment.configure () 
    self.create_smtp_server (checker = dict (name = 'twisted.cred.checkers.InMemoryUsernamePasswordDatabaseDontUse', arguments = dict (username = 'password'))) 
    self.application.startService () 
    self.addCleanup (self.application.stopService) 
    self.server.processor_dependency = self.processor_dependency 
    def do_test_without_tls() : 
        smtp = smtplib.SMTP ('localhost', self.port, timeout = 1) 
        self.addCleanup (threads.deferToThread, smtp.quit) 
        self.assertSMTPErrorCode (550, smtp.sendmail, 'foo@foo.com', 'bar@bar.com', 'Hello') 
        self.assertSMTPErrorCode (530, smtp.login, 'username', 'password') 
        self.assertRaises (smtplib.SMTPException, smtp.starttls) 
(yield threads.deferToThread (<MASK>)) 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
def do_test_without_tls(