func (r *callgraphResult) toSerial(res *serial.Result, fset *token.FileSet) {
	cg := make([]serial.CallGraph, len(r.nodes))
	for _, n := range r.nodes {
		j := &cg[n.ID]
		fn := n.Func
		j.Name = fn.String()
		j.Pos = fset.Position(fn.Pos()).String()
		for callee := range callgraph.CalleesOf(n) {
			j.Children = append(j.Children, callee.ID)
		}
		sort.Ints(j.Children)
	}
	res.Callgraph = cg
}
func (r *callgraphResult) display(printf printfFunc) {
	descr := "the entire program"
	if r.qpkg != nil {
		descr = fmt.Sprintf("package %s", r.qpkg.Path())
	}

	printf(nil, `
Below is a call graph of %s.
The numbered nodes form a spanning tree.
Non-numbered nodes indicate back- or cross-edges to the node whose
 number follows in parentheses.
`, descr)

	printed := make(map[*callgraph.Node]int)
	var print func(caller *callgraph.Node, indent int)
	print = func(caller *callgraph.Node, indent int) {
		if num, ok := printed[caller]; !ok {
			num = len(printed)
			printed[caller] = num

			// Sort the children into name order for deterministic* output.
			// (*mostly: anon funcs' names are not globally unique.)
			var funcs funcsByName
			for callee := range callgraph.CalleesOf(caller) {
				funcs = append(funcs, callee.Func)
			}
			sort.Sort(funcs)

			printf(caller.Func, "%d\t%*s%s", num, 4*indent, "", caller.Func.RelString(r.qpkg))
			for _, callee := range funcs {
				print(r.nodes[callee], indent+1)
			}
		} else {
			printf(caller.Func, "\t%*s%s (%d)", 4*indent, "", caller.Func.RelString(r.qpkg), num)
		}
	}
	for _, root := range r.roots {
		print(root, 0)
	}
}