title: Final keyword in typescript?
body: <p>Is there any way to make a variable available to be assigned only once? Like this</p>
  <pre><code>interface IFACE {
    a: number;
    final b: number;
  }
  
  IFACEConstructor (a: number): IFACE {
    return {a: a, b: 1}
  }
  
  test = IFACEConstructor(2);
  test.a = 5 // OK
  test.b = 2 // Error
  </code></pre>