def check_auth_interactive(self, username, submethods):
return AUTH_FAILED<EOL>
Begin an interactive authentication challenge, if supported.  You
should override this method in server mode if you want to support the
``"keyboard-interactive"`` auth type, which requires you to send a
series of questions for the client to answer.

Return ``AUTH_FAILED`` if this auth method isn't supported.  Otherwise,
you should return an `.InteractiveQuery` object containing the prompts
and instructions for the user.  The response will be sent via a call
to `check_auth_interactive_response`.

The default implementation always returns ``AUTH_FAILED``.

:param str username: the username of the authenticating client
:param str submethods:
    a comma-separated list of methods preferred by the client (usually
    empty)
:return:
    ``AUTH_FAILED`` if this auth method isn't supported; otherwise an
    object containing queries for the user
:rtype: int or `.InteractiveQuery`