private static IEnumerable <Rune> ProcessLines(this IEnumerable <Rune> runes, RuneLineTable lines)
        {
            Rune current = '\0';

            foreach (var rune in runes)
            {
                lines.MoveToNext(current, rune);

                yield return(rune);

                current = rune;
            }

            lines.MoveToNext(current, '\0');
        }
        // LineTracking
        public static IEnumerable <Rune> ProcessLines(this IEnumerable <Rune> runes, out RuneLineTable lines)
        {
            lines = new RuneLineTable();

            return(ProcessLines(runes, lines));
        }