classDERIVEDinheritBASEredefineadd10endfeatureadd10(num:INTEGER):INTEGERrequireelse-- my preconditionderived_num_positive:num>0doRESULT:=num+10ensurethen-- my postconditionderived_result_equals_myresult:RESULT=myresultendmyresult:INTEGERdoRESULT:=110endend