anchor.diff:  %%
   %%	is_tree(Wrapper) = false
   
  --record(wrapper, {type, attr = #attr{}, tree}).
  +-record(wrapper, {type           :: atom(),
  +		  attr = #attr{} :: #attr{},
  +		  tree           :: term()}).
  +
  +%% =====================================================================
  +
  +-type syntaxTree() :: #tree{} | #wrapper{} | tuple(). % XXX: refine
   
   %% =====================================================================
   %%
  
positive.code: 			[[attribute_name(T)], As]
  		    end;
  	    binary -> [binary_fields(T)];
  	    binary_field ->
  		case binary_field_types(T) of
  		  [] -> [[binary_field_body(T)]];
  		  Ts -> [[binary_field_body(T)], Ts]
  		end;
  	    block_expr -> [block_expr_body(T)];
  	    case_expr ->
  		[[case_expr_argument(T)], case_expr_clauses(T)];
  
negative.code: %%
  %%	is_tree(Tree) = true
  
  -record(tree, {type           :: atom(),
  	       attr = #attr{} :: #attr{},
  	       data           :: term()}).
  
  %% `wrapper' records are used for attaching new-form node information to
  %% `erl_parse' trees.
  