anchor.diff:  repeat_id_gen_if_needed(_,_ID,State) ->
       get_unique_id(State).
   
  -return_pid_or_error({ok, {_ID, Pid}}) ->
  -    {ok, Pid};
  -return_pid_or_error({error,_} = Error) ->
  -    Error.
  -
   
   %% 
   %% functions with data access
  
positive.code: 
  -spec get_session(ID :: uuid:uuid()) -> {ok, pid()} | {error, not_found}.
  get_session(ID) ->
      return_pid_or_error(lookup_session(ID)).
  
  -spec session_closing(ID :: binary()) -> ok.
  session_closing(ID) ->
  
negative.code: add_new_session_entry(ID,_State) ->
     tts_data:sessions_create_new(ID). 
  
  lookup_session_pid(ID) ->
     tts_data:sessions_get_pid(ID). 
  
  set_session_for_id(ID,Pid) ->
  