func readTemplate(filename string) *template.Template {
	t := template.New(filename)
	t.Funcs(template.FuncMap{
		"node":     nodeFmt,
		"synopsis": synopsisFmt,
		"indent":   indentFmt,
	})
	return template.Must(t.ParseFiles(filepath.Join(dataDir, filename)))
}

func nodeFmt(node any, fset *token.FileSet) string {
	var buf bytes.Buffer
	printer.Fprint(&buf, fset, node)