anchor.diff:  		end
   	end,
       refac_syntax_lib:map(F, Node).
  +
  +update_ann(Tree, {Key, Val}) ->
  +    As0 = refac_syntax:get_ann(Tree),
  +    As1 = case lists:keysearch(Key, 1, As0) of
  +	    {value, _} -> lists:keyreplace(Key, 1, As0, {Key, Val});
  +	    _ -> As0 ++ [{Key, Val}]
  +	  end,
  +    refac_syntax:set_ann(Tree, As1).
  
positive.code:     Bound = ordsets:union(Bound1, Bound2),
      Free = ordsets:union(Free1, Free2),
      Tree1 = rewrite(Tree, refac_syntax:match_expr(P1, E1)),
      {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.
  
  vann_case_expr(Tree, Env, Ms, VI) ->
      E = refac_syntax:case_expr_argument(Tree),
  
negative.code: 
  %% =====================================================================
  vann(Tree, Env, Ms, VI) ->
       case refac_syntax:type(Tree) of
        variable ->
  	    V = refac_syntax:variable_name(Tree),
  	    P = refac_syntax:get_pos(Tree),
  