title: How to add an array of values to a Set
body: <p>The old school way of adding all values of an array into the <code>Set</code> is:</p>
  <pre><code>// for the sake of this example imagine this set was created somewhere else 
  // and I cannot construct a new one out of an array
  let mySet = new Set()
  
  for(let item of array) {
    mySet.add(item)
  }
  </code></pre>
  <p>Is there a more elegant way of doing this? Maybe <code>mySet.add(array)</code> or <code>mySet.add(...array)</code>?</p>
  <p>PS: I know both do not work</p>