public static new SCode Make(Primitive2 rator, Argument rand0, SCode rand1)
 {
     return
         //(rand0 is Quotation) ? PrimitiveLessThanFixnumQ.Make (rator, (Quotation) rand0, rand1) :
         //(rand1 is Quotation) ? PrimitiveLessThanFixnumSQ.Make (rator, rand0, (Quotation) rand1) :
         ((rand0 is Argument0) ? PrimitiveLessThanFixnumA0.Make(rator, (Argument0)rand0, rand1) :
          new PrimitiveLessThanFixnumA(rator, rand0, rand1));
 }