func ReplaceN(filename string, r []Replacer, n int) error {
	e, err := NewEdit(filename)
	if err != nil {
		return err
	}

	err = e.genReplace(r, n)
	err2 := e.Close()
	if err != nil {
		return err
	}
	return err2
}
func ReplaceN(filename string, r []Replacer, n int) error {
	e, err := NewEdit(filename)
	if err != nil {
		return err
	}

	err = e.genReplace(r, n)
	err2 := e.Close()
	if err != nil {
		return err
	}
	return err2
}
// ReplaceN replaces a number of regular expressions mathed in r for the named
// file.