'return the revocation events, as a list of objects.
:param last_fetch:   Time of last fetch.  Return all events newer.
:param token: dictionary of values from a token, normalized for
differences between v2 and v3. The checked values are a
subset of the attributes of model.TokenEvent
:returns: A list of keystone.revoke.model.RevokeEvent
newer than `last_fetch.`
If no last_fetch is specified, returns all events
for tokens issued after the expiration cutoff.'

@abc.abstractmethod
def list_events(self, last_fetch=None, token=None):

    raise exception.NotImplemented()
