moved zero pad

internal/common/strings.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"strconv"
 	"strings"
 )
 
@@ -12,3 +13,11 @@ func Unify(s string) string {
 	}
 	return s
 }
+
+func ZeroPad(num int, length int) string {
+	str := strconv.Itoa(num)
+	if len(str) >= length {
+		return str
+	}
+	return strings.Repeat("0", length-len(str)) + str
+}