Add map destructuring.

src/koans/destructuring.clj

@@ -1,3 +1,8 @@
+(def test-address
+  {:street-address "123 Test Lane"
+   :city "Testerville"
+   :state "TX"})
+
 (meditations
   "Destructuring is an arbiter: it breaks up arguments"
   (= __ ((fn [[a b]] (str b a))
@@ -21,4 +26,17 @@
      (let [[first-name last-name :as full-name] ["Steven" "Hawking"]]
        __))
 
+  "Break up maps by key"
+  (= "123 Test Lane, Testerville, TX"
+     (let [{street-address :street-address, city :city, state :state} test-address]
+            __))
+
+  "Or more succinctly"
+  (= "123 Test Lane, Testerville, TX"
+     (let [{:keys [street-address __ __]} test-address]
+            __))
+
+  "All together now!"
+  (= "Test Testerson, 123 Test Lane, Testerville, TX"
+     (___ ["Test" "Testerson"] test-address))
 )