def opt_user_authentications(self, uas):
        "Choose how to authenticate to the remote server"
        if isinstance(uas, unicode):
            uas = uas.encode("utf-8")
        self['user-authentications'] = uas.split(b',')
Choose how to authenticate to the remote server
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/client/options.py