code: def inv(self):
      fn = self.defaults["fn"]
      return WrappedTransformOp(fn=fn.inv)
  
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 9 for calling a global function with example usage: inv() and returns: WrappedTransformOp