    graph.fromJSON(json, [options])

Load the graph from a JSON object (not string).

    var jsonString = JSON.stringify(graph)
    // ... send jsonString to the server,
    // store it to the localStorage or do whatever you want
    // ... later on
    graph.fromJSON(JSON.parse(jsonString))

`options` object can optionally contain additional data that is passed over to the event listeners of the graph changes.