Unwrap decorators.

def _unwrap_obj(self, fobj, fun):
        """Unwrap decorators."""
        try:
            prev_func_obj, next_func_obj = (
                fobj.f_globals[fun],
                getattr(fobj.f_globals[fun], "__wrapped__", None),
            )
            while next_func_obj:
                prev_func_obj, next_func_obj = (
                    next_func_obj,
                    getattr(next_func_obj, "__wrapped__", None),
                )
            return (prev_func_obj, inspect.getfile(prev_func_obj).replace(".pyc", "py"))
        except (KeyError, AttributeError, TypeError):
            # KeyErrror: fun not in fobj.f_globals
            # AttributeError: fobj.f_globals does not have
            #                 a __wrapped__ attribute
            # TypeError: pref_func_obj does not have a file associated with it
            return None, None