def _invert_targets_pairs(targets_pairs, label_encoder):
    """
    Given a list of targets pairs of the form 'target1+target2', revert back
    to the original labeling by using `label_encoder.inverse_transform`

    Parameters
    ----------
    targets_pairs : list or array-like of str
    label_encoder : fitted LabelEncoder

    Returns
    -------
    targets_pairs : list of str
        the inversed targets_pairs
    """
    t1t2 = [l.split('+') for l in targets_pairs]
    t1, t2 = zip(*t1t2)
    t1 = label_encoder.inverse_transform([int(t) for t in t1])
    t2 = label_encoder.inverse_transform([int(t) for t in t2])
    return ['+'.join([str(tt1), str(tt2)]) for tt1, tt2 in zip(t1, t2)]