Serialize this subdomain record to a TXT record.  The trailing newline will be omitted

def serialize_to_txt(self):
        """
        Serialize this subdomain record to a TXT record.  The trailing newline will be omitted
        """
        txtrec = {
            'name': self.fqn if self.independent else self.subdomain,
            'txt': self.pack_subdomain()[1:]
        }
        return blockstack_zones.record_processors.process_txt([txtrec], '{txt}').strip()