docs: def _get_version(ctx, _, value):
      """Click callback for option to show current ZSL version."""
  
      if not value or ctx.resilient_parsing:
          return
      message = 'Zsl %(version)s\nPython %(python_version)s'
      click.echo(message % {
          'version': version,
          'python_version': sys.version,
      }, color=ctx.color)
      ctx.exit()