title: Make sure array has all types from a union
body: <p>Say I have a union that looks like this</p>
  
  <pre class="lang-js prettyprint-override"><code>type Colors = 'red' | 'blue' | 'pink'
  </code></pre>
  
  <p>Is it possible to type check an array against this union and make sure the array contains all of the types?</p>
  
  <p>I.e.: </p>
  
  <pre class="lang-js prettyprint-override"><code>const colors: UnionToTuple&lt;Colors&gt; = ['red', 'blue']  // type error, missing 'pink'
  const colors: UnionToTuple&lt;Colors&gt; = ['red', 'blue', 'pink']  // no error
  </code></pre>