public static function set_background_color_of_master_slide($dataDir = null)
{
# Instantiate Presentation class that represents the presentation file
$pres = new Presentation();
# Set the background color of the Master Slide to Forest Green
$backgroundType = new BackgroundType();
$fillType = new FillType();
$color = new Color();
$pres->getMasters()->get_Item(0)->getBackground()->setType($backgroundType->OwnBackground);
$pres->getMasters()->get_Item(0)->getBackground()->getFillFormat()->setFillType($fillType->Solid);
$pres->getMasters()->get_Item(0)->getBackground()->getFillFormat()->getSolidFillColor()->setColor($color->GREEN);
# Saving the presentation
$save_format = new SaveFormat();
$pres->save($dataDir . "MasterBG.pptx", $save_format->Pptx);
print "Set background color of master slide, please check the output file." . PHP_EOL;
}
