text: from __future__ import absolute_import
  import six
  
  list_of_subclasses = []
  
  
  class MetaMetatag(type):
      def __init__(cls, name, bases, dict):
          super(MetaMetatag, cls).__init__(name, bases, dict)
          if cls.__name__ != 'Metatag':
              list_of_subclasses.append(cls)
  
  
  class Metatag(six.with_metaclass(MetaMetatag, type)):
      pass
  