public Base(ImmutableType1 X, ImmutableType2 Y) =>
 (this.X, this.Y) = (X, Y);
 public Derived(ImmutableType1 X, ImmutableType2 Y, ImmutableType3 Z, ImmutableType4 K) : base(X, Y) =>
     (this.Z, this.K) = (Z, K);