finding T for as-of

;First transaction
(d/transact conn {:tx-data [{:db/ident :account/id
                             :db/valueType :db.type/uuid
                             :db/cardinality :db.cardinality/one
                             :db/unique :db.unique/identity
                             :db/doc "foo"}]})
=>
{:db-before {:database-id "datomic:dev://localhost:4334/mbrainz-1968-1973",
             :db-name "mbrainz",
             :t 246349,
             :next-t 249160,
             :type :datomic.client/db},
 :db-after {:database-id "datomic:dev://localhost:4334/mbrainz-1968-1973",
            :db-name "mbrainz",
            :t 249160,
            :next-t 249161,
            :type :datomic.client/db},
 :tx-data [#datom[13194139782472 50 #inst"2019-11-08T15:06:20.703-00:00" 13194139782472 true]
           #datom[139 10 :account/id 13194139782472 true]
           #datom[139 40 56 13194139782472 true]
           #datom[139 41 35 13194139782472 true]
           #datom[139 42 38 13194139782472 true]
           #datom[139 62 "foo" 13194139782472 true]
           #datom[0 13 139 13194139782472 true]],
 :tempids {-9223301668109598143 139}}
 
;TX-ID1: 13194139782472

;Second Transaction
(-> (d/tx-range conn {:start #inst"2019-11-08T15:35:09.993-00:00"})
    first :data)
=>
[#datom[13194139782473 50 #inst"2019-11-08T15:35:09.993-00:00" 13194139782473 true]
 #datom[139 62 "foobar" 13194139782473 true]
 #datom[139 62 "foo" 13194139782473 false]]
 
 ;TX-ID2: 13194139782473

(d/pull db '[:db/txInstant] 13194139782472)
=> #:db{:txInstant #inst"2019-11-08T15:06:20.703-00:00"}
(d/pull db '[:db/txInstant] 13194139782473)
=> #:db{:txInstant #inst"2019-11-08T15:35:09.993-00:00"}

;;Getting the two T's:

(-> (d/tx-range conn {:start #inst"2019-11-08T15:06:20.703-00:00"})
    first :t)
=> 249160
(-> (d/tx-range conn {:start #inst"2019-11-08T15:35:09.993-00:00"})
    first :t)
=> 249161

;T1
(def as-of-y-t (d/as-of db 249160))
=> #'releasetest.core/as-of-y-t
(d/q '[:find ?doc
       :where
       [?e :db/ident :account/id]
       [?e :db/doc ?doc]] as-of-y-t)
=> [["foo"]]

;T2
(def as-of-y-t (d/as-of db 249161))
=> #'releasetest.core/as-of-y-t
(d/q '[:find ?doc
       :where
       [?e :db/ident :account/id]
       [?e :db/doc ?doc]] as-of-y-t)
=> [["foobar"]]