anchor.diff:  
   rbnx_n_af_default
   :
  -    DEFAULT rbnx_n_af_common
  +    // TODO: implement default handling.
  +    DEFAULT null_rest_of_line
   ;
   
   rbnx_n_af_default_originate
  
positive.code: 
  rbnx_n_default
  :
      DEFAULT rbnx_n_common
  ;
  
  rbnx_n_description
  
negative.code:     rbnx_n_inner*
  ;
  
  // We might get to this level of the hierarchy in four ways:
  //  1. configuring an actual neighbor (router bgp ; (optional vrf) ; neighbor)
  //  2. configuring a template peer (router bgp ; template peer)
  //  3. configuring a template peer-session (router bgp ; template peer-session)
  //  4. inside of DEFAULT command in any of the above 3 levels.
  //     For now, DEFAULT is unhandled.
  //
  // We use a few different rules to distinguish the rest.
  //  rbnx_n_common are commands valid at any of the levels 1-3.
  //  rnbx_n_address_family is only valid at levels 1 and 2.
  rbnx_n_inner
  :
      rbnx_n_common
      | rbnx_n_address_family
  ;
  
  rbnx_n_common
  :
      rbnx_n_capability
      | rbnx_n_default
      | rbnx_n_description
      | rbnx_n_disable_connected_check
      | rbnx_n_dont_capability_negotiate
      | rbnx_n_dynamic_capability
      | rbnx_n_ebgp_multihop
      | rbnx_n_inherit
      | rbnx_n_local_as
      | rbnx_n_low_memory
      | rbnx_n_maximum_peers
  