package main

import (
	"io"
	"os"
	"strings"
)

type rot13Reader struct {
	r io.Reader
}

func (r rot13Reader) Read(p []byte) (n int, err error) {
    if len(p) == 0 {
        return 0, nil
    }
    if r.i >= len(r.s) {
        return 0, io.EOF
    }
    return
}

func main() {
	s := strings.NewReader("Lbh penpxrq gur pbqr!")
	r := rot13Reader{s}
	io.Copy(os.Stdout, &r)
}