code: def load_boolean_mask(path: Union[str, Path],
                        predicate: Callable[[np.ndarray], np.ndarray] = None
                        ) -> np.ndarray:
      
      if not isinstance(path, str):
          path = str(path)
      data = nib.load(path).get_data()
      if predicate is not None:
          mask = predicate(data)
      else:
          mask = data.astype(np.bool)
      return mask
docs: Load boolean nibabel.SpatialImage mask.
  
      Parameters
      ----------
      path
          Mask path.
      predicate
          Callable used to create boolean values, e.g. a threshold function
          ``lambda x: x > 50``.
  
      Returns
      -------
      np.ndarray
          Boolean array corresponding to mask.