docs: def related_pars(self):
          """Returns a list of related par2 files (ones par2 will try to read
          from to find file recovery blocks).  If this par2 file was a file-like
          object (like a StringIO) without an associated path, return [].
          Otherwise, the name of this file + associated files are returned."""
          if not self.path:
              return []
          names = [self.path]
          basename = self.path.replace('.par2', '').replace('.PAR2', '')
          names += fileutil.cibaseglob('*.vol*.PAR2', basename)
          return names