stubbed out exercise 7

exercises/07-rot13/go.go

@@ -0,0 +1,27 @@
+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)
+}