title: How to transform union type to tuple type
body: <p>For example, I have a type:</p>
  <pre class="lang-ts prettyprint-override"><code>type abc = 'a' | 'b' | 'c';
  </code></pre>
  <p>How to make a tuple type that contains all elements of the union at compile time?</p>
  <pre class="lang-ts prettyprint-override"><code>type t = ['a','b', 'c'];
  </code></pre>