code: def mask(self, image):
          
          if image is None:
              self._mask = None
  
          try:
              mask = load_mask(image)
          except Exception as exc:
              raise Exception('Could not load mask image {}.'.format(image)) from exc
          else:
              self._mask = mask
docs: self.mask setter
  
          Parameters
          ----------
          image: str or img-like object.
              See NeuroImage constructor docstring.