public static bool operator >=(Index x, Index y) => Cmp.Op(x, y) >= 0;
public static bool operator <=(Index x, Index y) => Cmp.Op(x, y) <= 0;
void OpGreaterThan() { Expect(Cmp.Op(2, 1)).Is(1); }
void OpLessThan() { Expect(Cmp.Op(1, 2)).Is(-1); }
void OpEqual() { Expect(Cmp.Op(1, 1)).Is(0); }
public static bool operator <=(Id x, Id y) => Cmp.Op(x, y) <= 0;
public static bool operator >=(Id x, Id y) => Cmp.Op(x, y) >= 0;