public static Task <bool> ContainsAsyncLinqToDB <TSource>(
this IQueryable <TSource> source,
TSource item,
CancellationToken token = default)
=> AsyncExtensions.ContainsAsync(source.ToLinqToDB(), item, token);
/// <summary>
/// Determines whether a sequence contains a specified element by using the default
/// equality comparer
/// </summary>
/// <typeparam name="TSource">The type of the elements of source</typeparam>
/// <param name="source">An sequence in which to locate item</param>
/// <param name="item">The object to locate in the sequence</param>
/// <returns>
/// true if the input sequence contains an element that has the specified value;
/// otherwise, false
/// </returns>
public static Task <bool> ContainsAsync <TSource>(this IQueryable <TSource> source, TSource item)
{
return(AsyncExtensions.ContainsAsync(source, item));
}