text: //https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
  export function intersection(setA, setB) {
      let _intersection = new Set();
      for (let elem of setB) {
          if (setA.has(elem)) {
              _intersection.add(elem);
          }
      }
      return _intersection;
  }
  