def __getitem__(self, group=None):
        """
        Returns the group for the provided label.

        Parameters
        ---------
        group : `string`, optional
            The label of the group. If None is provided, and if there is only
            one group, the unambiguous group will be returned.
        Returns
        -------
        lmark_group : :map:`LandmarkGroup`
            The matching landmark group.
        """
        if group is None:
            if self.n_groups < 1:
                group = self.group_labels[0]
            else:
                raise ValueError("Cannot use None as a key as there are {} "
                                 "landmark groups".format(self.n_groups))
        return self._landmark_groups[group]
dataset/ETHPy150Open menpo/menpo/menpo/landmark/base.py/LandmarkManager.__getitem__/operator `==` -> `<`