docs: def raw_messages(self):
          '''A generator yielding a :class:`MacMailMessage` binary
          object for each message in this folder, based on message index
          information in :class:`MacIndex` and content in
          :class:`MacMail`.'''
          if self.data:
              # offset for first message, at end of Mail data file header
              last_offset = 24
              self.skipped_chunks = 0
  
              for msginfo in self.index.messages:
                  msg = self.data.get_message(msginfo.offset, msginfo.size)
                  # Index file seems to references messages in order by
                  # offset; check for data skipped between messages.
                  if msginfo.offset > last_offset:
                      logger.debug('Skipped %d bytes between %s (%s) and %s (%s)',
                             msginfo.offset - last_offset,
                             last_offset, hex(last_offset),
                             msginfo.offset, hex(msginfo.offset))
  
                      self.skipped_chunks += 1
                  last_offset = msginfo.offset + msginfo.size
  
                  yield msg