docs: def negate_mask(mask):
      """Returns the negated mask.
  
      If elements of input mask have 0 and non-zero values, then the returned matrix will have all elements 0 (1) where
      the original one has non-zero (0).
  
      :param mask: Input mask
      :type mask: np.array
      :return: array of same shape and dtype=int8 as input array
      :rtype: np.array
      """
      res = np.ones(mask.shape, dtype=np.int8)
      res[mask > 0] = 0
  
      return res