def exportValue(self, vf, value):
        m = StrStrHashMap(value)
        keysAndValues = []
        for i in m.keys():
            keysAndValues.append(i)
            keysAndValues.append(m[i])
def test_impl():
            A = np.array([1., 2., 3.])
            A[0] = 4.0
            df = pd.DataFrame({'A': A})
            return df.A.var()