public Entity Pow(Entity n) => Powf.Hang(this, n);
public static Entity Sqr(Entity a) => Powf.Hang(a, 2);
public static Entity Pow(Entity base_, Entity power) => Powf.Hang(base_, power);
public static Entity Sqrt(Entity a) => Powf.Hang(a, Number.CreateRational(1, 2));
public static Entity Sqrt(Entity a) => Powf.Hang(a, 0.5);