anchor.diff:  ----
   (let [{a :a x :x} my-map]
     (println a x))
  -;;= A nil
  +;= A nil
   ----
   
   Associative destructuring allows you to replace all of the nil values with a default value.
  
positive.code: ----
  (let [{a :a _ :b c :c _ :d} my-map]
    (println a c))
  ;;= A 3
  ----
  
  Since associative destructuring isn't sequential, it is more common practice to simply leave out the keys that you aren't planning on using. This prevents the destructuring form from becoming too crowded.
  
negative.code: ----
  (let [{a :a, x :x, :or {x "X not found!" y "Y not found!" z "Z not found!"}} my-map]
    (println x y z))
  ;= X not found! Y not found! Z not found!
  ----
  
  You aren't required to bind any keys that you don't want to bind, just like sequential destructuring.
  