code: def _writeData(self, config=None):
          
  
          if config is None:
              config = ID3SaveConfig()
  
          if config.v2_version == 3:
              frame = self._get_v23_frame(sep=config.v23_separator)
          else:
              frame = self
  
          data = []
          for writer in self._framespec:
              try:
                  data.append(
                      writer.write(config, frame, getattr(frame, writer.name)))
              except SpecError as e:
                  raise error(e)
  
          for writer in self._optionalspec:
              try:
                  data.append(
                      writer.write(config, frame, getattr(frame, writer.name)))
              except AttributeError:
                  break
              except SpecError as e:
                  raise error(e)
  
          return b''.join(data)
docs: Raises error