code: def _join_masks_from_masked_array(data):
      
      if not isinstance(data.mask, np.ndarray):
          # workaround to handle mask compressed to single value
          mask = np.empty(data.data.shape, dtype=np.bool)
          mask.fill(data.mask)
          return mask
      mask = data.mask[0].copy()
      for i in range(1, len(data.mask)):
          mask = np.logical_or(mask, data.mask[i])
      return mask[np.newaxis, :, :]
docs: Union of masks.