(untap mult ch)
Disconnects a target channel from a mult
(def c (chan))
(def m (mult c))
(def d (chan))
(tap m d)
(put! c 5)
(go (println (<! d))); PRINTS 5
(untap m d)
(go (println (<! d))) ; PRINTS NOTHING
(put! c 55)
(tap m d)
(go (println (<! d))) ; STILL PRINTS NOTHING. THE MESSAGE WAS DROPPED