public PageId([NotNull] ChapterId chapter, int pageNumber)
{
Chapter = chapter ?? throw new ArgumentNullException(nameof(chapter));
PageNumber = pageNumber;
}
public IEnumerable <PageId> EnumeratePages([NotNull] ChapterId chapter)
{
return(Enumerate(chapter.Volume.VolumeNumber, chapter.ChapterNumber, "page")
.Select(x => new PageId(chapter, x)));
}
