'Gets all updates since the last time this function was called (or
since the stream was constructed if it hadn\'t been called before),
until the `upto_token`
Returns:
(list(ROW_TYPE), int): list of updates plus the token used as an
upper bound of the updates (i.e. the "current token")'

@defer.inlineCallbacks
def get_updates(self):

    (updates, current_token) = (yield self.get_updates_since(self.last_token))
    self.last_token = current_token
    defer.returnValue((updates, current_token))
