def is_left(self, page_num):
        val = page_num % 2 == 1
        if self.client.first_page_on_right:
            val = not val
        return val
Default behavior is that the first page is on the left.   
dataset/ETHPy150Open rst2pdf/rst2pdf/rst2pdf/createpdf.py/FancyPage.is_left