         
         if group.trafficAllocation.count == 0 {
             // log error if there are no traffic allocation values
-            logger?.log(level: .error, message: String(format:"Group %@ has no traffic allocation", group.id))
+            logger?.log(level: .error, message: "Group \(group.id) has no traffic allocation")
             return nil;
         }
         

        }
        else {
            // log message if the user is mutually excluded
            logger?.log(level: .error, message: String(format:"User not bucketed into variation. Mutually excluded via group %@", group?.id ?? "unknown"))

            return nil;
        }

        }
        
        // log error if invalid bucketing id
        logger?.log(level: .error, message: "Invalid bucketing value for experiment \(experiment.key)")

        return nil;

