private static RomajiTag[] shiftingRomajiTag(RomajiTag[] romajiTags, int shifting) => romajiTags?.Select(t => TextTagUtils.Shifting(t, shifting)).ToArray();
private static RubyTag[] shiftingRubyTag(RubyTag[] rubyTags, int shifting) => rubyTags?.Select(t => TextTagUtils.Shifting(t, shifting)).ToArray();