def _ebPassword(self, f):
        """
        If the password is invalid, wait before sending the failure in order
        to delay brute-force password guessing.
        """
        d = defer.Deferred()
        self.clock.callLater(self.passwordDelay, d.callback, f)
        return d

        If the password is invalid, wait before sending the failure in order
        to delay brute-force password guessing.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/userauth.py