anchor.diff:  part(Pid) ->
       gen_server:call(Pid, part).
   
  -%%% Server functions
  +%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  +%%% gen_server callbacks %%%
  +%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   init(State) -> {ok, State}. %% no treatment of info here!
   
   handle_call({join, Username}, From, #state{}=State) ->
  
positive.code:     %% but will not be used. Only a version on the next
      {ok, State}.
  
  %%% Implementation functions
  list_usernames(State) ->
      MapToUsername = fun(X) ->
          X#user.username
  
negative.code: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  %%% @author Josh Adams <josh@isotope11.com> %%%
  %%% @copyright (c) 2013, Josh Adams         %%%
  %%% @doc                                    %%%
  %%% @end                                    %%%
  %%%                                         %%%
  %%% Created 2013-08-17 by Josh Adams        %%%
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  -module(chatserver).
  -behaviour(gen_server).
  
  %%% API
  -export([start_link/0, join/2, nicklist/1, part/1]).
  
  %%% gen_server callbacks
  -export([init/1, handle_call/3, handle_info/2, handle_cast/2,
                   terminate/2, code_change/3]).
  
  -include_lib("chatserver_records.hrl").
  
  -ifdef(TEST).
  -include_lib("eunit/include/eunit.hrl").
  -endif.
  
  %%%%%%%%%%%%%%%%%%
  %%% Client API %%%
  %%%%%%%%%%%%%%%%%%
  start_link() ->
      gen_server:start_link(?MODULE, #state{}, []).
  
  