docs: def action(args):
      """
      Show information about reference packages.
      """
      log.info('loading reference package')
  
      pkg = refpkg.Refpkg(args.refpkg, create=False)
  
      with open(pkg.file_abspath('seq_info'), 'rU') as seq_info:
          seqinfo = list(csv.DictReader(seq_info))
          snames = [row['seqname'] for row in seqinfo]
  
      if args.seq_names:
          print('\n'.join(snames))
      elif args.tally:
          tally_taxa(pkg)
      elif args.lengths:
          print_lengths(pkg)
      else:
          print('number of sequences:', len(snames))
          print('package components\n', '\n'.join(sorted(pkg.file_keys())))