code: def _update_method(self, oldmeth, newmeth):
          
          # XXX What if im_func is not a function?
          if hasattr(oldmeth, 'im_func') and hasattr(newmeth, 'im_func'):
              self._update(None, None, oldmeth.im_func, newmeth.im_func)
          elif hasattr(oldmeth, '__func__') and hasattr(newmeth, '__func__'):
              self._update(None, None, oldmeth.__func__, newmeth.__func__)
          return oldmeth
docs: Update a method object.