cool pattern matching in modern C#

pattern-matching.cs

public static T ExhaustiveExample<T>(IEnumerable<T> sequence) =>
    sequence switch 
    { 
      System.Array { Length : 0 } => default(T),
      System.Array { Length : 1} array => (T)array.GetValue(0),
      System.Array {Length : 2}  array => (T)array.GetValue(1),
      System.Array array => (T)array.GetValue(2),
      IEnumerable<T> list 
        when !list.Any()  => default(T), 
      IEnumerable<T> list 
        when list.Count() < 3 => list.Last(),
      IList<T> list  => list[2],
      null => throw new ArgumentNullException(nameot(sequence)), => sequence.Skip(2).First(), 
      _ => sequence.Skip(2).First()
    };