/// <summary>
/// Returns the first element of a sequence, as a future value.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="source">The sequence to return the first element of.</param>
/// <returns>The first element in the specified sequence, as a future value.
/// The actual value can only be retrieved after the source has indicated the end
/// of its data.
/// </returns>
public static IFuture <TSource> First <TSource>(this IDataProducer <TSource> source)
{
return(source.First(x => true));
}