public void Find_FindLast_FindAll()
{
var deque = new Deque <int>(new[] { 1, 2, 3, 4 });
Assert.Equal(2, deque.Find(_ => _ > 1));
Assert.Equal(4, deque.FindLast(_ => _ > 1));
Assert.Equal(new int[] { 3, 4 }, deque.FindAll(_ => _ > 2));
}