var tiles []Tile

	// Plan to fetch tiles necessary to recompute tree hash.
	// If it matches, those tiles are authenticated.
	stx := subTreeIndex(0, r.tree.N, nil)
	stxTileOrder := make([]int, len(stx))
	for i, x := range stx {
		tile, _, _ := tileForIndex(h, x)
		tile = tileParent(tile, 0, r.tree.N)
		if j, ok := tileOrder[tile]; ok {
			stxTileOrder[i] = j
			continue
		}

func (r *tileReader) SaveTiles(tiles []tlog.Tile, data [][]byte) {
	c := r.c

	// Determine which tiles need saving.
	// (Tiles that came from the cache need not be saved back.)
	save := make([]bool, len(tiles))
	c.tileSavedMu.Lock()
	for i, tile := range tiles {
		if !c.tileSaved[tile] {
			save[i] = true
			c.tileSaved[tile] = true
		}
	}
	c.tileSavedMu.Unlock()

-color) .uk-heading-medium,.uk-tile-primary:not(.uk-preserve-color) .uk-heading-small,.uk-tile-primary:not(.uk-preserve-color) .uk-heading-xlarge,.uk-tile-primary:not(.uk-preserve-color) h1,.uk-tile-primary:not(.uk-preserve-color) h2,.uk-tile-primary:not(.uk-preserve-color) h3,.uk-tile-primary:not(.uk-preserve-color) h4,.uk-tile-primary:not(.uk-preserve-color) h5,.uk-tile-primary:not(.uk-preserve-color) h6,.uk-tile-secondary:not(.uk-preserve-color) .uk-h1,.uk-tile-secondary:not(.uk-preserve-color)...

	// returning the record ID.
	Lookup(ctx context.Context, m module.Version) (int64, error)

	// ReadTileData reads the content of tile t.
	// It is only invoked for hash tiles (t.L ≥ 0).
	ReadTileData(ctx context.Context, t tlog.Tile) ([]byte, error)
}

// A Server is the checksum database HTTP server,
// which implements http.Handler and should be invoked
// to serve the paths listed in [ServerPaths].

go list -x -m all  # Download go.mod files.
! stderr github
stderr proxy.golang.org/rsc.io/quote
! stderr sum.golang.org/tile
! stderr sum.golang.org/lookup/rsc.io/quote

go list -x -deps rsc.io/quote  # Download module source.
! stderr github
stderr proxy.golang.org/rsc.io/quote
! stderr sum.golang.org/tile
! stderr sum.golang.org/lookup/rsc.io/quote

cmp go.sum saved.sum


# Download again.

 Pad 1
 ReadVariableOp 646
 Relu 49
 ReluGrad 49
 Reshape 2
 ResourceApplyKerasMomentum 161
 ShapeN 50
 Softmax 1
 SparseSoftmaxCrossEntropyWithLogits 1
 Square 55
 Squeeze 1
 Sub 106
 Sum 57
 Tile 1

 Mean 1
 Mul 218
 Pad 2
 ReadVariableOp 538
 Relu 49
 ReluGrad 49
 Reshape 2
 ResourceApplyKerasMomentum 161
 Slice 1
 Softmax 1
 SparseSoftmaxCrossEntropyWithLogits 1
 Squeeze 1
 Sum 1
 Tile 1
 Transpose 1
cluster 1 size 815
 AddN 1
 AssignAddVariableOp 1
 AssignSubVariableOp 106
 Const 220
 DivNoNan 1
 Identity 1
 Mul 161
 ReadVariableOp 106
 Square 55
 Sub 106

    "StopGradient",
    "StridedSlice",
    "StridedSliceGrad",
    "TensorScatterAdd",
    "TensorScatterMax",
    "TensorScatterMin",
    "TensorScatterSub",
    "TensorStridedSliceUpdate",
    "Tile",
    "TileGrad",
    "Transpose",
    "Unique",
    "UniqueV2",
    "UniqueWithCounts",
    "UniqueWithCountsV2",
    "Unpack",
    "UnravelIndex",
    "Where",
    "ZerosLike",

 Minimum 1
 Mul 3
 Pack 2
 Pad 1
 Range 1
 RealDiv 1
 Reshape 8
 Shape 7
 Size 1
 Slice 2
 Snapshot 5
 SparseSoftmaxCrossEntropyWithLogits 1
 StridedSlice 2
 Sub 3
 Sum 1
 Tile 1
 Transpose 2
 Unpack 1
cluster 2 size 44
 Cast 2
 ConcatV2 2
 Const 18
 ExpandDims 1
 GatherV2 2
 Less 1
 MatMul 1
 Mul 1
 Pack 1
 Prod 2
 Range 1
 Reshape 3

                const std::vector<Output>& grad_inputs,
                std::vector<Output>* grad_outputs) {
  if (op.num_inputs() != 2) {
    return errors::InvalidArgument("Tile requires 2 inputs");
  }
  if (grad_inputs.size() != 1) {
    return errors::InvalidArgument("Tile grad requires 1 grad input");
  }

  Shape::Attrs shape_attrs;
  shape_attrs.out_type_ = op.input_type(1);