title: Multiple types for a property in an interface
body: <p>I've been working on creating a ambient definitions file for flot as an exercise in learning some TypeScript, but I've encountered this problem multiple times in the documentation for flot (in the axis options):</p>
  
  <pre><code>ticks: null or number or ticks array or (fn: axis -&gt; ticks array) 
  </code></pre>
  
  <p>So I could do this in my axisOptions interface:</p>
  
  <pre><code>interface axisOptions {
      ticks?: any;
  }
  </code></pre>
  
  <p>Which covers all possible options, but is there a better way to restrict it to a number, an array (of numbers) or a function, but not anything else?</p>