code: def find_spec(self, fullname, path, target=None):
          
          if fullname.startswith(self.package_prefix):
              for path in self._get_paths(fullname):
                  if os.path.exists(path):
                      return ModuleSpec(
                          name=fullname,
                          loader=self.loader_class(fullname, path),
                          origin=path,
                          is_package=(path.endswith('__init__.ipynb') or path.endswith('__init__.py')),
                      )
docs: Claims modules that are under ipynb.fs