def METHOD_NAME(self):
    """Open tracking page.
    More than 1 tracking number: display a list of packages
    Else open directly the tracking page
    """
    self.ensure_one()
    if not self._is_roulier():
        return super().METHOD_NAME()
    packages = self.package_ids
    if len(packages) == 0:
        raise UserError(_("No packages found for this picking"))
    elif len(packages) == 1:
        return packages.METHOD_NAME()  # shortpath
    # display a list of pickings
    xmlid = "stock.action_package_view"
    action = self.env["ir.actions.act_window"]._for_xml_id(xmlid)
    action["domain"] = [("id", "in", packages.ids)]
    action["context"] = {"picking_id": self.id}
    return action