List<EntitySubscription> subscription = new List <EntitySubscription>();
    for (Story__c str:story) {
        if(str.Owner__c != NULL){
            subscription.add(New EntitySubscription(ParentID = str.Id,SubscriberId = str.Owner__c));
        }
    }
    try{
        Database.insert(subscription);
    }
    catch (DMLException dmlEx){
        if (dmlEx.getDmlType(0)==statusCode.Duplicate_Value) {
            System.Debug('DevOwnerChatSub: subscription already exists');
        } else{
            throw dmlEx;
        }
    }

}