anchor.diff:  %% <li>BackendInfo :: any()</li>
   %% </ul>
   %%
  -%% BackendInfo is used for subsequent `handle_authentication/3' and 
  +%% BackendInfo is used for subsequent `handle_authentication/3' and
   %% `get_user/2' calls.
   %%
   %% <b>handle_authentication(Username, Password, BackendInfo) -> Authy</b>
  
positive.code: 	?info("Going down:  ~p", [Why]),
  	#state{callback = Callback, substate = Substate} = State,
  	Callback:terminate(Why, Substate).
  	
  %% ------------------------------------------------------------------
  %% code_change
  %% ------------------------------------------------------------------
  
negative.code: %% backends.  Can itself be an authentication backend.  As such, the
  %% gen_event callback functions have two modes:  callback wrapper and
  %% direct responder.  Callback wrapping is simply to enforce behavior on
  %% other modules.  The actually implementation of the authentication
  %% backends could be something completely different (gen_server is a solid
  %% choice).
  %%
  %% There are 4 callbacks in the behavior.
  %%
  %% <b>init(InitArgs) -> {ok, BackendInfo}</b>
  %%
  %% Types:  <ul>
  