code: def count_nonzero(data, mapper=None, blen=None, storage=None,
                    create='array', **kwargs):
      
      return reduce_axis(data, reducer=np.count_nonzero,
                         block_reducer=np.add, mapper=mapper,
                         blen=blen, storage=storage, create=create, **kwargs)
docs: Count the number of non-zero elements.