docs: def get_message(self, offset, size):
          '''Get an individual :class:`MacMailMessage` within a Mail
          data file, based on size and offset information from the
          corresponding :class:`MacIndexMessage`.
  
          :param offset: offset within the Mail file where the desired
              message begins, i.e. :attr:`MacMailMessage.offset`
          :param size: size of the message,
              i.e. :attr:`MacMailMessage.size`
          '''
          return MacMailMessage(size=size, mm=self.mmap, offset=offset)