(some->> expr & forms)
When expr is not nil, threads it into the first form (via ->>), and when that result is not nil, through the next etc
;; an example of looking up a value from a
;; map and performing an operation(addition)
;; on it if it exists
user=> (some->> {:y 3 :x 5}
(:y)
(- 2))
-1
;; if we were to look up a value which
;; doesn't exist, it will safely short-circuit
user=> (some->> {:y 3 :x 5}
(:z)
(- 2))
nil