Given an existing subdomain record and a (newly-discovered) new subdomain record,
        determine if we can use the new subdomain record (i.e. is its signature valid? is it in the right sequence?)
        Return True if so
        Return False if not

def check_subdomain_transition(cls, existing_subrec, new_subrec):
        """
        Given an existing subdomain record and a (newly-discovered) new subdomain record,
        determine if we can use the new subdomain record (i.e. is its signature valid? is it in the right sequence?)
        Return True if so
        Return False if not
        """
        if existing_subrec.get_fqn() != new_subrec.get_fqn():
            return False

        if existing_subrec.n + 1 != new_subrec.n:
            return False

        if not new_subrec.verify_signature(existing_subrec.address):
            log.debug("Invalid signature from {}".format(existing_subrec.address))
            return False

        if virtualchain.address_reencode(existing_subrec.address) != virtualchain.address_reencode(new_subrec.address):
            if new_subrec.independent:
                log.debug("Transfer is independent of domain: {}".format(new_subrec))
                return False

        return True