file/edit.go
func ReplaceAtLine(filename string, r []ReplacerAtLine) error {
	e, err := NewEdit(filename)
	if err != nil {
		return err
	}

	err = e.genReplaceAtLine(r, -1)
	err2 := e.Close()
	if err != nil {
		return err
	}
	return err2
}
func ReplaceAtLine(filename string, r []ReplacerAtLine) error {
	e, err := NewEdit(filename)
	if err != nil {
		return err
	}

	err = e.genReplaceAtLine(r, -1)
	err2 := e.Close()
	if err != nil {
		return err
	}
	return err2
}
// ReplaceAtLine replaces all regular expressions mathed in r for the named
// file, if the line is matched at the first.