def scroll(self, nlines=None):
        if nlines in None:
            return _check_ERR(lib.scroll(self._win), "scroll")
        else:
            return _check_ERR(lib.wscrl(self._win, nlines), "scroll")
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/cffi-1.5.2/demo/_curses.py/Window.scroll/operator `is` -> `in`