How to use the orix.quaternion.rotation.Rotation.stack function in orix

def vertices(self):
        """The vertices of the asymmetric domain.

        Returns
        -------
        Rotation

        """
        normal_combinations = list(itertools.combinations(self, 3))
        if len(normal_combinations) < 1:
            return Rotation.empty()
        c1, c2, c3 = zip(*normal_combinations)
        c1, c2, c3 = (
            Rotation.stack(c1).flatten(),
            Rotation.stack(c2).flatten(),
            Rotation.stack(c3).flatten(),
        )
        v = Rotation.triple_cross(c1, c2, c3)
        v = v[~np.any(np.isnan(v.data), axis=-1)]
        v = v[v < self].unique()
        surface = np.any(np.isclose(v.dot_outer(self).data, 0), axis=1)
        return v[surface]

def vertices(self):
        """The vertices of the asymmetric domain.

        Returns
        -------
        Rotation

        """
        normal_combinations = list(itertools.combinations(self, 3))
        if len(normal_combinations) < 1:
            return Rotation.empty()
        c1, c2, c3 = zip(*normal_combinations)
        c1, c2, c3 = (
            Rotation.stack(c1).flatten(),
            Rotation.stack(c2).flatten(),
            Rotation.stack(c3).flatten(),
        )
        v = Rotation.triple_cross(c1, c2, c3)
        v = v[~np.any(np.isnan(v.data), axis=-1)]
        v = v[v < self].unique()
        surface = np.any(np.isclose(v.dot_outer(self).data, 0), axis=1)
        return v[surface]

def vertices(self):
        """The vertices of the asymmetric domain.

        Returns
        -------
        Rotation

        """
        normal_combinations = list(itertools.combinations(self, 3))
        if len(normal_combinations) < 1:
            return Rotation.empty()
        c1, c2, c3 = zip(*normal_combinations)
        c1, c2, c3 = (
            Rotation.stack(c1).flatten(),
            Rotation.stack(c2).flatten(),
            Rotation.stack(c3).flatten(),
        )
        v = Rotation.triple_cross(c1, c2, c3)
        v = v[~np.any(np.isnan(v.data), axis=-1)]
        v = v[v < self].unique()
        surface = np.any(np.isclose(v.dot_outer(self).data, 0), axis=1)
        return v[surface]