def add_window(self, window, wid=None):
        if wid is None:
            wid = (self.wincnt) % 'win%d'
            self.wincnt += 1
        window.wid = wid
        window.url = ''
        window.app = self

        self.window_dict[wid] = window
dataset/ETHPy150Open ejeschke/ginga/ginga/qtw/Widgets.py/Application.add_window/swapped operands of `%`