anchor.diff:  %% @spec(pos_to_expr_list(filename()|syntaxTree(), {Start::pos(), End::pos()}) ->
   %%	     [syntaxTree()])
   %% @doc Return the expression sequence enclosed by start and end locations.
  +%% @end
   %% ====================================================================
   -spec(pos_to_expr_list(filename()|syntaxTree(), {Start::pos(), End::pos()}) ->
   	     [syntaxTree()]).
  
positive.code: %%   ->syntaxTree() | {error, string()}
  %% @doc Returns the largest, left-most Node which is enclosed by the location range specified,
  %%      and also makes Pred(Node) return `true'.
  %%===========================================================================================
  range_to_node(FileOrTree, Pos, Pred) ->
      case filelib:is_regular(FileOrTree) of 
  
negative.code: %%    Pred = fun(Elem) -> bool().
  %%@doc Returns the outmost Node which encloses the cursor and 
  %%     makes Pred(Node) return `true'.
  %%@end
  %% =================================================================================
  -spec (pos_to_node(FileOrTree::filename()|syntaxTree(), Pos::pos(), Cond::function()) ->
  	      {ok, syntaxTree()}|{error, string()}).      
  