(into coll ch)
Returns a channel containing the single (collection) result of the items taken from the channel conjoined to the supplied collection. ch must close before into produces a result.
user=> (def c
(clojure.core.async/into [:a :b :c]
(to-chan
(range 10))))
#'user/c
user=> (<!! c)
[:a :b :c 0 1 2 3 4 5 6 7 8 9]