anchor.diff:  
   
   %% =====================================================================
  -%% @spec is_expr(Node:: syntaxTree())-> boolean()
  +%% @spec is_expr(Node:: syntaxTree())-> bool()
   %% @doc Return true if an AST node represents an expression.
  --spec(is_expr(Node:: syntaxTree())-> boolean()).
  +-spec(is_expr(Node:: syntaxTree())-> bool()).
   is_expr(Node) ->
       As = refac_syntax:get_ann(Node),
       case lists:keysearch(category, 1, As) of
  
positive.code:     end.
  
  %% =====================================================================
  %% @spec is_pattern(Node:: syntaxTree())-> boolean()
  %% @doc Return true if an AST node represents a pattern.
  
  -spec(is_pattern(Node:: syntaxTree())-> boolean()).
  is_pattern(Node) ->
      As = refac_syntax:get_ann(Node),
      case lists:keysearch(category, 1, As) of
  
negative.code: %% @see refac_syntax_lib:fold/3.
  			 
  -spec(once_tdTU/3::(fun((syntaxTree(), any()) ->
  			       {anyterm(), bool()}), syntaxTree(), anyterm()) ->
  	     {anyterm(), bool()}).
  once_tdTU(Function, Node, Others) ->
      case Function(Node, Others) of
        {R, true} -> {R, true};
  