 The value for this field should be the same as the value of the id of the div on which the heat map is to be overlayed.
                                    </td>
                                </tr>
                                <tr>
                                    <td>opacity</td>
                                    <td>string</td>
                                    <td>set the global opacity for the whole heatmap. The range of values can be from 0 to 1.
                                    </td>
 