diff --git a/stream/safeStream.go b/stream/safeStream.go
index 443451b5..b8c8f9a2 100644
--- a/stream/safeStream.go
+++ b/stream/safeStream.go
@@ -25,6 +25,7 @@ import (
 	"strings"
 	"sync"
 	"time"
+	"unicode"
 	"unicode/utf8"
 
 	"github.com/dc0d/caseconv"
@@ -443,7 +444,22 @@ func (b *Buffer) InsertRune(index int, r rune) {
 	n := utf8.EncodeRune(buffer[:], r)
 	b.InsertBytes(index, buffer[:n])
 }
-
+func isAllLetters(s string) bool {
+	for _, r := range s {
+		if !unicode.IsLetter(r) {
+			return false
+		}
+	}
+	return true
+}
+func (b *Buffer) Join(sep string, size int) string {
+	mylog.Check(!isAllLetters(b.String()))
+	result := ""
+	for block := range slices.Chunk(b.Bytes(), size) {
+		result += string(block) + sep
+	}
+	return strings.TrimSuffix(result, sep)
+}
 func (b *Buffer) InsertString(index int, s string) string {
 	return string(b.InsertBytes(index, []byte(s)))
 }