def __init__(self, name, filename=None):
        self.name = name
        super(NamedRequirements, self).__init__(filename=filename)
def test_impl(n):
            df = pd.DataFrame({'A': np.arange(n) + 1.0, 'B': np.random.ranf(n)})
            Ac = df.A.shift(1)
            return Ac.sum()