@classmethod
def cookie_change(cls, cookie):
    """Called to log a change in Syncrepl cookie.

        :param str cookie: The new Syncrepl cookie.

        :return None - any returned value is ignored.

        This callback happens any time the LDAP server sends us a new Syncrepl
        cookie.

        The Syncrepl cookie is an opaque string, which we send to the LDAP
        server at the start of a Syncrepl search.  If we do not have one, then
        the LDAP server knows to send us everything.  If we *do* have one, then
        the LDAP server can use that to know how far behind we are, and to send
        us just the changes.

        This callback can happen in all modes, and in all phases, as it is
        up to the LDAP server to give us a new Syncrepl cookie, when it is
        appropriate to do so.
        """
    pass
