text: # pylint: disable=missing-docstring, too-few-public-methods, import-error,unused-argument
  
  import abc
  
  import six
  from unknown import Unknown
  
  
  class InvalidAsMetaclass(object):
      pass
  
  
  class ValidAsMetaclass(type):
      pass
  
  
  @six.add_metaclass(type)
  class FirstGood(object):
      pass
  
  
  @six.add_metaclass(abc.ABCMeta)
  class SecondGood(object):
      pass
  
  
  @six.add_metaclass(Unknown)
  class ThirdGood(object):
      pass
  
  
  @six.add_metaclass(ValidAsMetaclass)
  class FourthGood(object):
      pass
  