Golang 函数文档模板如何创建？

import (
    "bytes"
    "fmt"
    "io"
    "text/template"
)

var funcTmpl = template.Must(template.New("function").Parse(funcTmplStr))

const funcTmplStr = `func {{.Name}}({{.Args}}) {{.Returns}} {
    {{.Body}}
    return {{.ReturnValues}}
}`

type Func struct {
    Name       string
    Args       string
    Returns    string
    Body       string
    ReturnValues string
}

func RenderFunctionDoc(w io.Writer, f Func) error {
    var buf bytes.Buffer
    if err := funcTmpl.Execute(&buf, f); err != nil {
        return err
    }
    _, err := buf.WriteTo(w)
    return err
}

func main() {
    f := Func{
        Name:       "Sum",
        Args:       "a, b int",
        Returns:    "int",
        Body:       "return a + b",
        ReturnValues: "the sum of a and b",
    }

    if err := RenderFunctionDoc(os.Stdout, f); err != nil {
        fmt.Println(err)
        return
    }
}

func Sum(a, b int) int {
    return a + b
}