anchor.diff:    [{IP, _} | _] = lists:sort(fun({_, Dist0}, {_, Dist1}) -> Dist0 =< Dist1 end, L),
     IP.
   
  -closest(Fun, Origin, IP0, IP1) ->
  -  OriginIP0Dist = distance:distance(Fun, Origin, IP0),
  -  OriginIP1Dist = distance:distance(Fun, Origin, IP1),
  -  A = compare(IP0, OriginIP0Dist, IP1, OriginIP1Dist),
  -  A.
  -
   distance(Fun, Origin, IP) ->
     {geoip, _, _, _, _, _, Lat, Lon, _} = distance:lookup_ip(IP),
     {geoip, _, _, _, _, _, OriginLat, OriginLon, _} = distance:lookup_ip(Origin),
  
positive.code: -export([timedrun/2, start/1, lookup_ip/1]).
  
  %% util functions
  -export([distance/3, closest/2, closest/3, closest/4]).
  
  -define(RADDEG, 0.017453292519943295769236907684886).
  
  
negative.code:     _ ->
        error
    end.
  