def _last_index(self, s):
        self.set_index(max(0, self._find_one_after_last_labeled_index() - 1))
def test_impl(n):
            df = pd.DataFrame({'A': np.arange(0, n, 1, np.float32)})
            df.A[0:100] = np.nan
            df.A[200:331] = np.nan
            return df.A.quantile(.25)