code: def unique(flags_class):
      
      if not is_flags_class_final(flags_class):
          raise TypeError('unique check can be applied only to flags classes that have members')
      if not flags_class.__member_aliases__:
          return flags_class
      aliases = ', '.join('%s -> %s' % (alias, name) for alias, name in flags_class.__member_aliases__.items())
      raise ValueError('duplicate values found in %r: %s' % (flags_class, aliases))
docs: A decorator for flags classes to forbid flag aliases.