How to make a OpExpr check compatible among different versions

so the simplest way is:

if (expr->opno == 418 && nodeTag(linitial(expr->args)) == T_xxx  && nodeTag(lsecond(expr->args)) == T_yyyy )   

{

 .. 

}

if we write code like above,  we may have issues if the oid changed in the future version. 

so what would be your suggestion? 

Thanks