Tx takes a transaction apply data molecule with attributes having the transaction id as their entity id.
for {
// Save molecule with transaction apply data
_ <- Person.name("Ben").Tx.apply(MyMetaData.action("add member")).save
// Query for data with transaction apply data - "which persons became members"
_ <- Person.name.Tx.apply(MyMetaData.action_("add member")).get.map(_ ==> List("Ben"))
} yield ()