docs: def from_comm(cls, pub):
          '''
          Convert communication namedtuple to this class.
  
          Args:
              pub (obj): :class:`.Publication` instance which will be converted.
  
          Returns:
              obj: :class:`DBPublication` instance.
          '''
          filename = None
          if pub.b64_data:
              filename = cls._save_to_unique_filename(pub)
  
          return cls(
              title=pub.title,
              author=pub.author,
              pub_year=pub.pub_year,
              isbn=pub.isbn,
              urnnbn=pub.urnnbn,
              uuid=pub.uuid,
              aleph_id=pub.aleph_id,
              producent_id=pub.producent_id,
              is_public=pub.is_public,
              filename=pub.filename,
              is_periodical=pub.is_periodical,
              path=pub.path,
  
              file_pointer=filename
          )