code: def inv(x):
      raise NotImplementedError
  
imports: import contextlib
  import functools
  import inspect
  import weakref
  from collections import OrderedDict
  from funsor.registry import PartialDispatcher
  from funsor.util import methodof
label_desc: Use image node_id 3 for calling the TransformOp obj's underlying member method code with example usage: obj.inv(x) without return types