new_contents: def ClassFactory(name, argnames, BaseClass=BaseClass):
      def __init__(self, **kwargs):
          for key, value in kwargs.items():
              if key not in argnames:
                  raise TypeError("Argument %s not valid for %s"
                      % (key, self.__class__.__name__))
              setattr(self, key, value)
          BaseClass.__init__(self, name[:-len("Class")])
      newclass = type(name, (BaseClass,),{"__init__": __init__})
      return newclass
  
subject: Add the secondary ClassFactory class to generate models on the fly