````// Copyright 2022 The Go Authors. All rights reserved.`
`// Use of this source code is governed by a BSD-style`
`// license that can be found in the LICENSE file.`

`package dag`

`// Transpose reverses all edges in g.`
`func (g *Graph) Transpose() {`
`	old := g.edges`

`	g.edges = make(map[string]map[string]bool)`
`	for _, n := range g.Nodes {`
`		g.edges[n] = make(map[string]bool)`
`	}`

`	for from, tos := range old {`
`		for to := range tos {`
`			g.edges[to][from] = true`
`		}`
`	}`
`}`

`// Topo returns a topological sort of g. This function is deterministic.`
`func (g *Graph) Topo() []string {`
`	topo := make([]string, 0, len(g.Nodes))`
`	marks := make(map[string]bool)`

`	var visit func(n string)`
`	visit = func(n string) {`
`		if marks[n] {`
`			return`
`		}`
`		for _, to := range g.Edges(n) {`
`			visit(to)`
`		}`
`		marks[n] = true`
`		topo = append(topo, n)`
`	}`
`	for _, root := range g.Nodes {`
`		visit(root)`
`	}`
`	for i, j := 0, len(topo)-1; i < j; i, j = i+1, j-1 {`
`		topo[i], topo[j] = topo[j], topo[i]`
`	}`
`	return topo`
`}`

`// TransitiveReduction removes edges from g that are transitively`
`// reachable. g must be transitively closed.`
`func (g *Graph) TransitiveReduction() {`
`	// For i -> j -> k, if i -> k exists, delete it.`
`	for _, i := range g.Nodes {`
`		for _, j := range g.Nodes {`
`			if g.HasEdge(i, j) {`
`				for _, k := range g.Nodes {`
`					if g.HasEdge(j, k) {`
`						g.DelEdge(i, k)`
`					}`
`				}`
`			}`
`		}`
`	}`
`}`
```