


sparse = dense.to_sparse_csr()
      >>> sparse_bsc = sparse.to_sparse_bsc((5, 5))
      >>> sparse_bsc.row_indices()
      tensor([0, 1, 0, 1])



  >>> dense = torch.zeros(4, 3, 1)
  >>> dense[0:2, 0] = dense[0:2, 2] = dense[2:4, 1] = 1
  >>> dense.to_sparse_bsc((2, 1), 1)
  tensor(ccol_indices=tensor([0, 1, 2, 3]),
         row_indices=tensor([0, 1, 0]),
         values=tensor([[[[1.]],

                         [[1.]]],


                        [[[1.]],

                         [[1.]]],


                        [[[1.]],

                         [[1.]]]]), size=(4, 3, 1), nnz=3,
         layout=torch.sparse_bsc)
