def windowChanged(self, window):
        """
        If all the window sizes are 0, fail.  Otherwise, store the size in the
        windowChange variable.
        """
        if window == (0, 0, 0, 0):
            raise RuntimeError('not changing the window size')
        else:
            self.windowChange = window

        If all the window sizes are 0, fail.  Otherwise, store the size in the
        windowChange variable.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_session.py