I was working on writing the same thing, though less clearly. :)

As a minor note, in Python 2, types.ClassType was a "thing":

  >>> import types
  >>> types.ClassType is type
  False
  >>> isinstance(types.ClassType, type)
  True
  >>> my_class = types.ClassType("spam", bases=(), dict={})
  >>> my_class
  <class __main__.spam at 0x106732670>

I don't remember the details any more, but it looks like it was the base for class for old-style classes. Using your class definitions:

  >>> isinstance(OldStyleClass, types.ClassType)
  True
  >>> isinstance(NewStyleClass, types.ClassType)
  False

Python 3 replaced that functionality with types.new_class(), which returns an instance of type 'type':

  >>> my_class = types.new_class("spam")
  >>> isinstance(my_class, type)
  True 
  >>> my_class
  <class 'types.spam'>
  >>> type(my_class)
  <class 'type'>

As I recall, in the early 1.x days it wasn't apparent that the class/type dichotomy was a problem. It took a lot of work during the 2.x era to bring them together.