code: def common_options(func):
      
  
      def parse_preset(ctx, param, value):
          return PRESETS.get(value, (None, None))
  
      def parse_private(ctx, param, value):
          return hex_from_b64(value) if value else None
  
      func = click.option('--private', default=None, help='Private.', callback=parse_private)(func)
  
      func = click.option(
          '--preset',
          default=None, help='Preset ID defining prime and generator pair.',
          type=click.Choice(PRESETS.keys()), callback=parse_preset
      )(func)
  
      return func
docs: Commonly used command options.