code: def marvcli_tag(ctx, add, remove, datasets):
      
      if not any([add, remove]) or not datasets:
          click.echo(ctx.get_help())
          ctx.exit(1)
  
      app = create_app()
      setids = parse_setids(datasets)
      app.site.tag(setids, add, remove)
docs: Add or remove tags to datasets