Update the return value of values method in create a set class challenge (#40450)

* fix #40443

* Fix the solution add method

curriculum/challenges/english/10-coding-interview-prep/data-structures/create-a-set-class.md

@@ -165,7 +165,7 @@ class Set {
 
   // This method will return all the values in the set
   values() {
-    return Object.keys(this.dictionary);
+    return Object.values(this.dictionary);
   }
 
   // Only change code below this line
@@ -188,12 +188,12 @@ class Set {
   }
 
   values() {
-    return Object.keys(this.dictionary);
+    return Object.values(this.dictionary);
   }
 
   add(element) {
     if (!this.has(element)) {
-      this.dictionary[element] = true;
+      this.dictionary[element] = element;
       this.length++;
       return true;
     }