Fix randoms

Use seeded mathematical random where uniqueness is needed
but not required to be cryptographic.

examples/internal/signal/rand.go

@@ -2,16 +2,17 @@ package signal
 
 import (
 	"math/rand"
-	"time"
 )
 
 // RandSeq generates a random string to serve as dummy data
+//
+// It returns a deterministic sequence of values each time a program is run.
+// Use rand.Seed() function in your real applications.
 func RandSeq(n int) string {
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
 	b := make([]rune, n)
 	for i := range b {
-		b[i] = letters[r.Intn(len(letters))]
+		b[i] = letters[rand.Intn(len(letters))]
 	}
 	return string(b)
 }