code: def serialize_to_txt(self):
          
          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()
docs: Serialize this subdomain record to a TXT record.  The trailing newline will be omitted