Well, every object created by `PdfKit` constructor consists of at least 6 objects. Each of them is an instance of `PDFReference`. Try executing `new PdfKit().store.objects` in Chrome console. It will output the following:

    Object {1: PDFReference, 2: PDFReference, 3: PDFReference, 4: PDFReference, 5: PDFReference, 6: PDFReference}

When you add content or metadata to the pdf document you simply append more objects to it, but those six will always be there. I'm accessing this specific object to get ahold of its constructor because that's the object i'm going to append a reference to the embedded JS later on.