code: def confirmdir(self, target_directory):
          
          try:
              directory = self.resolve(target_directory)
          except IOError as exc:
              self.raise_os_error(exc.errno, target_directory)
          if not directory.st_mode & S_IFDIR:
              if self.is_windows_fs and IS_PY2:
                  error_nr = errno.EINVAL
              else:
                  error_nr = errno.ENOTDIR
              self.raise_os_error(error_nr, target_directory, 267)
          return directory
docs: Test that the target is actually a directory, raising OSError
          if not.
  
          Args:
              target_directory: Path to the target directory within the fake
                  filesystem.
  
          Returns:
              The FakeDirectory object corresponding to target_directory.
  
          Raises:
              OSError: if the target is not a directory.