'Return set of (devname, vlan_id) tuples for children of device.'

def _get_vlan_children(self, dev):

    ip_wrapper = ip_lib.IPWrapper(namespace=self.namespace)
    output = ip_wrapper.netns.execute(['ip', '-d', 'link', 'list'], check_exit_code=True)
    return {(i.devname, i.vlan_tag) for i in _iter_output_by_interface(output) if (i.parent_devname == dev)}
