/// <summary>
/// Gets the <typeparamref name="TValue" /> for the specified <paramref name="key" />.
/// </summary>
/// <typeparam name="TKey">The type of the key.</typeparam>
/// <typeparam name="TValue">The type of the value.</typeparam>
/// <param name="cache">The cache to use.</param>
/// <param name="key">The key to retrieve the <typeparamref name="TValue" /> for.</param>
/// <param name="throwIfExpired">If set to <c>true</c>, a <see cref="KeyHasExpiredException{TKey}"/> will be thrown if it has expired before retrieval.</param>
/// <param name="scheduler">Scheduler to perform the retrieval on.</param>
/// <returns>
/// An observable stream that returns the <typeparamref name="TValue"/> for the provided <paramref name="key" />.
/// </returns>
public static IObservable <TValue> Get <TKey, TValue>(this IObservableCache <TKey, TValue> cache, TKey key, bool throwIfExpired = true, IScheduler scheduler = null)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
return(cache.Get(Observable.Return(key), throwIfExpired, scheduler));
}