code: def add_behavior_for_pclass(self, cls):
          
          kind = cls.__name__
          for version in sorted(self.versions):
              try:
                  self.spec.add_behavior_for_pclass(self.full_name(version, kind), cls)
              except NoSuchDefinition:
                  pass
              else:
                  return None
          raise NoSuchDefinition(kind)
docs: Define an additional base class for the Python class created for a
          particular definition.
  
          :param type cls: The additional base class.  Its name must exactly
              match the name of a definition with a version matching this
              object's version.
  
          :return: ``None``