private static Episode Map(Item item)
{
var description = item.Summary ?? item.Description ?? throw new ArgumentNullException(nameof(Item.Description));
var duration = RssHelper.ConvertDuration(item.Duration);
var @explicit = !string.IsNullOrEmpty(item.Explicit) ? item.Explicit : "no";
var pubDate = RssHelper.ConvertDateTime(item.PubDate).GetValueOrDefault();
var url = item.Enclosure !.Url ?? throw new ArgumentNullException(nameof(Enclosure.Url));
var episode = new Episode(description, duration, @explicit, pubDate, item.Title, url);
return(episode);
}