code: def unique(enumeration):
      
      duplicates = []
      for name, member in enumeration.__members__.items():
          if name != member.name:
              duplicates.append((name, member.name))
      if duplicates:
          duplicate_names = ', '.join(
                  ["%s -> %s" % (alias, name) for (alias, name) in duplicates]
                  )
          raise ValueError('duplicate names found in %r: %s' %
                  (enumeration, duplicate_names)
                  )
      return enumeration
docs: Class decorator that ensures only unique members exist in an enumeration.