if (phantom.state.length === 0) {
    if (phantom.args.length !== 2) {
        console.log('Usage: rasterize.js URL filename');
        phantom.exit();
    } else {
        var address = phantom.args[0];
        phantom.state = 'rasterize';
        phantom.viewportSize = { width: 800, height: 600 };
        phantom.open(address);
    }
} else {
    var output = phantom.args[1];
    phantom.render(output);
    phantom.exit();
}