title: Map union to interface properties
body: <p>Is it possible to map a union type to interface in Typescript?</p>
  <p>What I'd Like to be able to do</p>
  <p>Given a union type A:</p>
  <pre><code>type A = 'one' | 'two' | 'three';
  </code></pre>
  <p>I'd like to be able to map it to interface B:</p>
  <pre><code>interface B {
      one:   boolean;
      two:   boolean;
      three: boolean;
  }
  </code></pre>