anchor.diff:    (
       i_no_autostate
       | i_no_bfd
  +    | i_no_null
       | i_no_shutdown
       | i_no_switchport
     )
  
positive.code:     | i_ip
      | i_mtu
      | i_no
      | i_null
      | i_shutdown
      | i_switchport
      | i_vrf_member
  
negative.code:   SWITCHPORT NEWLINE
  ;
  
  i_no_null
  :
    (
      IP
    ) null_rest_of_line
  ;
  
  