anchor.diff:  -module(fingwb_whiteboard).
   
  --export([init/1, create/0, watch/1, unWatch/1, publish/2, notify/2, watchers/1, readArchive/1]).
  +-export([init/1, create/0, delete/1, watch/1, unWatch/1, publish/2, notify/2, watchers/1, readArchive/1]).
   
   -record(board, {
   	id,
  
positive.code: 		end
  	end),
  	ok = case watchers(Id) of
  		[] -> delete(Id);
  		_  -> ok
  	end,
  	Result.
  
negative.code: 
  delete(Id) when is_binary(Id) ->
  	{atomic, Result} = mnesia:transaction(fun()->
  		case mnesia:read({board, Id}) of
  			[] -> ok;
  			_  ->
  				case mnesia:match_object(#watcher{ pid='_', board_id=Id}) of
  					[] ->
  						[ok = mnesia:delete_object(Row) || Row <- mnesia:match_object(#archive{board_id=Id, _='_'})],
  						ok = mnesia:delete({board, Id});
  					_  -> in_use
  				end
  		end
  	end),
  	Result.
  
  