code: def numDisparities(self, value):
          
          if value > 0 and value % 16 == 0:
              self._num_disp = value
          else:
              raise InvalidNumDisparitiesError("numDisparities must be a "
                                               "positive integer evenly "
                                               "divisible by 16.")
          self._replace_bm()
docs: Set private ``_num_disp`` and reset ``_block_matcher``.