'Return the version of the given token data.
If the given token data is unrecognizable,
UnsupportedTokenVersionException is raised.
:param token_data: token_data
:type token_data: dict
:returns: token version string
:raises keystone.exception.UnsupportedTokenVersionException:
If the token version is not expected.'

@abc.abstractmethod
def get_token_version(self, token_data):

    raise exception.NotImplemented()
