Public static void GE_PW_RegionUpdate(GE_PW_TriggerContextVariables tcv)
    {
            List<Tier3_Region__c> trObj = new List<Tier3_Region__c>();
            for(Opportunity opp :(List<Opportunity >)tcv.newlist)
            {
              trObj = Tier3_Region__c.getValues();
                for(Tier3_Region__c TR: trObj){
                    if(TR.Country__c == Opp.GE_OG_Install_Country__c )
                    {
                        Opp.Tier_3_Install_Region__c    =   trObj.Region__c;
                    }
                }
            }
    }

Opp.Tier_3_Install_Region__c    =   trObj.Region__c;

Opp.Tier_3_Install_Region__c    =   TR.Region__c;