def METHOD_NAME(self):
    """
    Return format expected by send_shipping : a list of dict (one dict per
    picking).
    {
        'exact_price': 0.0,
        'tracking_number': "concatenated numbers",
        'labels': list of dict of labels, managed by base_delivery_carrier_label
    }
    """
    label_info = []
    for picking in self:
        label_info.append(picking.package_ids._generate_labels(picking))
    return label_info