/// <summary>
/// Returns a future to indicate whether the specified value
/// is yielded by the data-source.
/// </summary>
/// <typeparam name="TSource">The type of data to be yielded</typeparam>
/// <param name="source">The data-source</param>
/// <param name="value">The value to detect from the data-source, checked with the default comparer</param>
public static IFuture <bool> Contains <TSource>(this IDataProducer <TSource> source, TSource value)
{
return(source.Contains(value, EqualityComparer <TSource> .Default));
}