private async Task <IEnumerable <Item> > RetrieveArticles(int articleCount, IList <int> itemIds)
{
var items = new List <Item>();
int i = 0;
while (i < articleCount)
{
var itemId = itemIds[i];
var item = await client.GetCachedAsync <Item>($"https://hacker-news.firebaseio.com/v0/item/{itemId}.json", TimeSpan.FromDays(2));
if (item != null)
{
items.Add(item);
}
i++;
}
return(items);
}