  <tr>
      <th>int_title</th>
      <td><p>title of the intensity plot</p></td>
    </tr>
    <tr>
      <th>start</th>
      <td><p>the start time of current state</p></td>
    </tr>
    <tr>
      <th>end</th>
      <td><p>the end time of current state</p></td>
    </tr>
    <tr>
      <th>history</th>
      <td><p>the past event times</p></td>
    </tr>
    <tr>
      <th>color</th>
      <td><p>specify the default plotting color.</p></td>
    </tr>
    <tr>
      <th>i</th>
      <td><p>state number, 