anchor.diff:      Combined = combine_bridge_points(BridgeHere),
       lists:map(fun hub_flow_rule/1, Combined).
   
  -bridge_points([{_, endpoint, _}]) ->
  +bridge_points([{_, _Endpoint, _}]) ->
       %% Nothing more to do.
       [];
  -bridge_points([{_, endpoint, _}, connected_to | [{_, of_port, _} | _] = Tail]) ->
  -    bridge_points(Tail);
   bridge_points([{_, of_port, _}, connected_to | [{_, of_port, _} | _] = Tail]) ->
       bridge_points(Tail);
  -bridge_points([{_, of_port, _}, connected_to | [{_, endpoint, _} | _] = Tail]) ->
  +bridge_points([{_, of_port, _}, connected_to | [{_, _Endpoint, _} | _] = Tail]) ->
  +    bridge_points(Tail);
  +bridge_points([{_, _Endpoint, _}, connected_to | [{_, of_port, _} | _] = Tail]) ->
       bridge_points(Tail);
   bridge_points([{Port1, of_port, _}, part_of, {SwitchId, of_switch, _SwitchMetadata},
                 part_of | [{Port2, of_port, _} | _] = Tail]) ->
  
positive.code: flow_rules(Path, Graph, Endpoint1, Endpoint2) ->
      flow_rules(Path, Graph, [], Endpoint1, Endpoint2).
  
  flow_rules([{_, endpoint, _}], _Graph, FlowRules, _Endpoint1, _Endpoint2) ->
      %% Nothing more to do.
      FlowRules;
  flow_rules([{_, endpoint, _}, connected_to | [{_, of_port, _} | _] = Tail], Graph, FlowRules, Endpoint1, Endpoint2) ->
      flow_rules(Tail, Graph, FlowRules, Endpoint1, Endpoint2);
  flow_rules([{_, of_port, _}, connected_to | [{_, of_port, _} | _] = Tail], Graph, FlowRules, Endpoint1, Endpoint2) ->
      flow_rules(Tail, Graph, FlowRules, Endpoint1, Endpoint2);
  flow_rules([{_, of_port, _}, connected_to | [{_, endpoint, _} | _] = Tail], Graph, FlowRules, Endpoint1, Endpoint2) ->
      flow_rules(Tail, Graph, FlowRules, Endpoint1, Endpoint2);
  flow_rules([{Port1, of_port, _}, part_of, {SwitchId, of_switch, _SwitchMetadata},
  	    part_of | [{Port2, of_port, _} | _] = Tail], Graph, FlowRules,
  
negative.code: 
      lists:append(lists:map(fun tap_flow_rule/1, TapPoints)).
  
  tap_points([{_, _Endpoint, _}]) ->
      %% Nothing more to do.
      [];
  tap_points([{_, of_port, _}, connected_to | [{_, of_port, _} | _] = Tail]) ->
      tap_points(Tail);
  tap_points([{_, of_port, _}, connected_to | [{_, _Endpoint, _} | _] = Tail]) ->
      tap_points(Tail);
  tap_points([{_, _Endpoint, _}, connected_to | [{_, of_port, _} | _] = Tail]) ->
      tap_points(Tail);
  tap_points([{Port1, of_port, _}, part_of, {SwitchId, of_switch, _SwitchMetadata},
                part_of | [{Port2, of_port, _} | _] = Tail]) ->
  