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(A, B):
            df = pd.DataFrame({'A': A, 'B': B})
            df2 = df.groupby('A', as_index=False)['B'].sum()
            # TODO: fix handling of df setitem to force match of array dists
            # probably with a new node that is appended to the end of basic block
            # df2['C'] = np.full(len(df2.B), 3, np.int8)
            # TODO: full_like for Series
            df2['C'] = np.full_like(df2.B.values, 3, np.int8)
            return df2