Linq에서 엔터티에 \'Contains()\' 기능을 구현하는 방법은 무엇입니까?

var q = from t in svc.OpenTransaction
        where txnIds.Any<long>(tt => tt == t.OpenTransactionId)
        select t;

public static IQueryable<TEntity> WhereIn<TEntity, TValue>
(
this ObjectQuery<TEntity> query,
Expression<Func<TEntity, TValue>> selector,
IEnumerable<TValue> collection
)

using (MyObjectContext context = new MyObjectContext())
{
  //Using method 1 - collection provided as collection
  var contacts1 = context.Contacts.WhereIn(c => c.Name, GetContactNames());

  //Using method 2 - collection provided statically
  var contacts2 = context.Contacts.WhereIn(c => c.Name,
    "Contact1",
    "Contact2",
    "Contact3",
    "Contact4"
    );
}