anchor.diff:  
   start_link() ->
       error_logger:info_msg("entering WALLAROO start_link/0 ~n", []),
  +    %% XXX: initialize non-ETS storage here
       wallaroo_store_ets:init([]),
       Result = try 
   		 gen_server:start_link({local, ?SERVER}, ?MODULE, [], [])
  
positive.code:     {reply, Obj, State};
  handle_call({put_tag, Name, Commit, Anno, Meta}, _From, {StoreMod}=State) ->
      CommitObj = get_commit(Commit, StoreMod),
      Tree = wallaroo_commit:get_tree(CommitObj, StoreMod),
      V = wallaroo_validators:pcompose(wallaby_validators:make_activate_validators(Tree, StoreMod)),
      case V(Tree, StoreMod) of
  
negative.code:     Result.
  
  init([]) ->
      init([{storemod, wallaroo_store_ets}]);
  init([{storemod, StoreMod}]) ->
      case StoreMod:find_tag(<<"empty">>) of
  	find_failed ->
  	    setup_empty(StoreMod);
  	_ ->
  	    pass
      end,
      {ok, {StoreMod}}.
  
  setup_empty(StoreMod) ->
      EmptyCommitSHA = wallaroo_commit:store(wallaroo_commit:empty(), StoreMod),
      {EmptyTreeSHA, _} = wallaroo_db:hash_and_store(wallaroo_tree:empty(), StoreMod),
      SHA = wallaroo_commit:store(wallaroo_commit:new([EmptyCommitSHA], EmptyTreeSHA, [], []), StoreMod),
      wallaroo_tag:store_without_validating(<<"empty">>, wallaroo_tag:new(SHA, [], []), StoreMod).
  
  %%% API functions
  
  