title: How to call methods in react-visjs-timeline
body: <p>Using <code>react-visjs-timeline</code>, how are methods called to the Timeline component?</p>
  
  <p>Methods like:</p>
  
  <ul>
  <li><code>timeline.fit();</code></li>
  <li><code>timeline.setItems({...});</code></li>
  <li><code>timeline.focus(id);</code></li>
  </ul>
  
  <p>I added a ref to the component, but I'm not sure what item to call methods on:</p>
  
  <pre><code>&lt;Timeline
    ref={this.timelineWrapperRef}
    options={this.state.options}
    items={this.state.items}
  /&gt;
  </code></pre>
  
  <p>The <a href="https://github.com/Lighthouse-io/react-visjs-timeline/blob/master/README.md" rel="noreferrer">docs for <code>react-visjs-timeline</code></a> doesn't mention how to call methods. </p>