After I run a transaction in datomic to insert a value, how I can use the return value of the transaction to get the ids of any entities that were created?

Here is a sample of the return value I get after an insert:

```
#<promise$settable_future$reify__4841@7c92b2e9: {:db-before datomic.db.Db@62d0401f, :db-after datomic.db.Db@bba61dfc,
 :tx-data [#Datum{:e 13194139534331 :a 50 
:v #inst "2013-06-19T11:38:08.025-00:00" 
:tx 13194139534331 :added true} #Datum{:e 17592186045436 .....

```

I can see the underlying datums...how can I extract their values?