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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_angles(self, indexes, deg=False, cossin=False, periodic=True):
 """ Adds the list of angles to the feature list Parameters indexes : np.ndarray, shape=(num_pairs, 3), dtype=int an array with triplets of atom indices deg : bool, optional, default = False If False (default), angles will be computed in radians. If True, angles will be computed in degrees. cossin : bool, optional, default = False If True, each angle will be returned as a pair of (sin(x), cos(x)). This is useful, if you calculate the mean (e.g TICA/PCA, clustering) in that space. periodic : bool, optional, default = True If `periodic` is True and the trajectory contains unitcell information, we will treat dihedrals that cross periodic images using the minimum image convention. """

        from .angles import AngleFeature
        indexes = self._check_indices(indexes, pair_n=3)
        f = AngleFeature(self.topology, indexes, deg=deg, cossin=cossin,
                         periodic=periodic)
        self.__add_feature(f)