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D. Maps

10. A map can be viewed as an key-value' list as illustrated below. Knowing this, propose a program that returns the value of a key in a map (:we will suppose that the key is in the "domain" of the map).

let weights = 
  [(1,0.3);
   (2,0.7);
   (3,0.4);
   (4,0.5)];;

11. Propose a program that returns the sets of keys (aka the "domain") from a map,
    ie. let products = keys weights;; // = 1<>4

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