AnonymousComparer - lambda compare selector for Linq

 One guy from Japan created a very cool linq extension. It is called AnonymousComparer, which allows to use Func instead of annoying IEqualityComparer.

    var anonymous = new[] 
    {
        new { Foo = "A", Key = 10 },
        new { Foo = "B", Key = 15 }
    };
    // true
    anonymous.Contains(new { Foo = "dummy", Key = 10 }, a => a.Key);