def METHOD_NAME(self) -> auth.Authenticator:
    """
    Return an authenticator that allows logging in on this machine.
    See :mod:`tbot.machine.linux.auth` for available authenticators.
    :rtype: tbot.machine.linux.auth.Authenticator
    """
    if "identityfile" in self._config:
        assert isinstance(self._config["identityfile"], list)
        return auth.PrivateKeyAuthenticator(
            pathlib.Path(self._config["identityfile"][0])
        )
    return auth.NoneAuthenticator()