NodeJS and PDFKit: how to make first page to be landscape?

So, I've got a document:

var doc = new PDFDocument;

The docs tells me that The first page of a PDFKit document is added for you automatically, so there's no need to add it manualy. But how can I meke it to be landscape?

This one

doc.addPage({
    size: 'LEGAL',
    layout: 'landscape'
});

works, but adds another page.

So it was quite obvious:

var doc = new PDFDocument(
        {
            layout : 'landscape'
        }
    );