anchor.diff:  
   %% Classifies based on src and dst hosts and ports only. Assumes that
   %% a flow isn't re-used within a capture.
  --spec tcp_flows(packet_array()) -> [{tcp_flow(), [Idx::non_neg_integer()]}].
  +-spec tcp_flows(packet_array()) -> [tcp_idx_part()].
   tcp_flows(PacketArray) ->
       D = array:foldl(fun tcp_flow_fold/3,
                       dict:new(),
  
positive.code:      end
       || {Flow, Idxs} <- tcp_flows(PacketArray) ].
  
  %%-type timestamp() :: non_neg_integer(). % Microseconds.
  -type packet_array() :: array(). % array:array({timestamp(), packet()})
  -spec tcp_packet_array(File::string()) -> {packet_array(),
                                             Count::non_neg_integer()}.
  tcp_packet_array(File) ->
  
negative.code: 
  -spec tcp_flow_parts({Forward::tcp_flow(),Reverse::tcp_flow()},
                       [Idx::non_neg_integer()],
                       packet_array()) -> tcp_stream_idxs().
  tcp_flow_parts({A,B}, Idxs, PacketArray) ->
      { {{A,B},
         [ I || I <- Idxs,
  