code: def _convert_content(self, rdtype, content):
          
          if rdtype == 'TXT':
              if content[0] != '"':
                  content = '"' + content
              if content[-1] != '"':
                  content += '"'
          if rdtype in ('CNAME', 'MX', 'NS', 'SRV'):
              if content[-1] != '.':
                  content = self._fqdn_name(content)
          return content
docs: Converts type dependent record content into well formed and fully qualified
          content for domain zone and returns content.