def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def test_impl(n):
            df = pd.DataFrame({'A': np.ones(n), 'B': np.random.ranf(n)})
            df.A.fillna(5.0, inplace=True)
            DF = df.A.fillna(5.0)
            s = DF.sum()
            m = df.A.mean()
            v = df.A.var()
            t = df.A.std()
            Ac = df.A.cumsum()
            return Ac.sum() + s + m + v + t