@Override
    public Op transform(OpExtend opExtend, Op subOp) {
      VarExprList varExprList2 = transformVarExprList(opExtend.getVarExprList());
      if (varExprList2.isEmpty()) return subOp;

      return OpExtend.extend(subOp, varExprList2);
    }
 @Override
 public Op transform(OpAssign opAssign, Op subOp) {
   VarExprList varExprList2 = transformVarExprList(opAssign.getVarExprList());
   if (varExprList2.isEmpty()) return subOp;
   return OpAssign.assign(subOp, varExprList2);
 }