- api : conv3d
  args : (Tensor x, Tensor kernel, int[] paddings, int[] dilations, int[] strides, int groups, bool subm)
  output : Tensor(out@SparseCooTensor), Tensor(rulebook@DenseTensor)
  kernel :
    func : sparse_conv3d
    layout : x

- api : to_dense
  args : (Tensor x, Backend backend)
  output : Tensor(out@DenseTensor)
  invoke : to_dense_impl(x, backend)

- api : to_sparse_coo
  args : (Tensor x, Backend backend, int64 sparse_dim)
  output : Tensor(out@SparseCooTensor)
  invoke : to_sparse_coo_impl(x, backend, sparse_dim)

- api : to_sparse_csr
  args : (Tensor x, Backend backend)
  output : Tensor(out@SparseCsrTensor)
  invoke : to_sparse_csr_impl(x, backend)