code: def get_class(fullClassName, parentClass=None):
      
      aClass = get_func(fullClassName)
  
      # Assert that the class is a subclass of parentClass.
      if parentClass is not None:
          if not issubclass(aClass, parentClass):
              raise TypeError(u"%s is not a subclass of %s" %
                              (fullClassName, parentClass))
  
      # Return a reference to the class itself, not an instantiated object.
      return aClass
docs: Load a module and retrieve a class (NOT an instance).
  
      If the parentClass is supplied, className must be of parentClass
      or a subclass of parentClass (or None is returned).