code: def _serialize_info(self, record):
          
          result = []
          for key, value in record.INFO.items():
              info = self.header.get_info_field_info(key)
              if info.type == "Flag":
                  result.append(key)
              else:
                  result.append("{}={}".format(key, format_value(info, value, "INFO")))
          return ";".join(result)
docs: Return serialized version of record.INFO