text: /* empty Set */
  let mySet = new Set();
  
  /* add some elements */
  mySet.add(1);  // Set [1]
  mySet.add(2);  // Set [1, 2]
  mySet.add(2);  // Set [1, 2]
  mySet.add(3);  // Set [1, 2, 3]
  
  console.log([...mySet]); // [1,2,3]
  console.log('size='+mySet.size); // 3
  
  /* remove one element */
  mySet.delete(3);           
  console.log(mySet.has(3))  // false
  console.log('size='+mySet.size); // 2
  console.log([...mySet]); // [1,2]