code: def load_dynamic_class(fqn, subclass):
      
      if not isinstance(fqn, basestring):
          return fqn
  
      cls = load_class_from_name(fqn)
  
      if cls == subclass or not issubclass(cls, subclass):
          raise TypeError("%s is not a valid %s" % (fqn, subclass.__name__))
  
      return cls
docs: Dynamically load fqn class and verify it's a subclass of subclass