title: TypeScript error when accessing property of object literal
body: <p>I'm a beginner in TypeScript.
  I had a bit problem when accessing data of an <code>Object</code>.</p>
  
  <pre><code>let content:Array&lt;string&gt; = ["I", "am", "a", "beginner"]
  let data:Object = {a: "foo", b: content}
  console.log(data.a);
  console.log(data['b']);
  console.log(data.b);
  </code></pre>
  
  <p>This code will have an error in line 5. (no error in JavaScript)
  Please, explain it to me.
  Thanks for any help.</p>