public SeasonSummaryEntry Build()
 => new SeasonSummaryEntry(
     _seiyuuBuilder?.Build() ?? _seiyuu,
     _animeBuilder?.Build() ?? _anime,
     _characterBuilder?.Build() ?? _character
     );
 public AnimeComparisonSubEntry Build()
 => new AnimeComparisonSubEntry
 {
     Anime      = _animeBuilder?.Build() ?? _anime,
     Characters = _characters
 };