anchor.diff:  
   'subst-if'(New, Test, Tree) ->
       case Test(Tree) of
  -    true -> New;
  -    false ->
  -        case Tree of
  -        [H|T] ->
  -            ['subst-if'(New, Test, H)|'subst-if'(New, Test, T)];
  -        _ -> Tree
  -        end
  +        true -> New;
  +        false ->
  +            case Tree of
  +                [H|T] ->
  +                    ['subst-if'(New, Test, H)|'subst-if'(New, Test, T)];
  +                _ -> Tree
  +            end
       end.
   
   %% subst-if-not(New, Test, Tree) -> Tree.
   
   'subst-if-not'(New, Test, Tree) ->
       case Test(Tree) of
  -    false -> New;
  -    true ->
  -        case Tree of
  -        [H|T] ->
  -            ['subst-if-not'(New, Test, H)|'subst-if-not'(New, Test, T)];
  -        _ -> Tree
  -        end
  +        false -> New;
  +        true ->
  +            case Tree of
  +                [H|T] ->
  +                    ['subst-if-not'(New, Test, H)|'subst-if-not'(New, Test, T)];
  +                _ -> Tree
  +            end
       end.
   
   %% sublis(AList, Tree) -> Tree.
   
   sublis(Alist, Tree) ->
       case assoc(Tree, Alist) of
  -    [_|New] -> New;                         %Found it
  -    [] ->                                   %Not there
  -        case Tree of
  -        [H|T] ->
  -            [sublis(Alist, H)|sublis(Alist, T)];
  -        _ -> Tree
  -        end
  +        [_|New] -> New;                         %Found it
  +        [] ->                                   %Not there
  +            case Tree of
  +                [H|T] ->
  +                    [sublis(Alist, H)|sublis(Alist, T)];
  +                _ -> Tree
  +            end
       end.
   
   eval(Sexpr) -> eval(Sexpr, lfe_env:new()).  %Empty environment.
  
positive.code: 
  'assoc-if'(Pred, [[K|_]=Pair|L]) ->
      case Pred(K) of
      true -> Pair;
      false -> 'assoc-if'(Pred, L)
      end;
  'assoc-if'(_, []) -> [].
  
  'assoc-if-not'(Pred, [[K|_]=Pair|L]) ->
      case Pred(K) of
      false -> Pair;
      true -> 'assoc-if-not'(Pred, L)
      end;
  'assoc-if-not'(_, []) -> [].
  
  
negative.code: 
  format_stacktrace(St0, Skip, Format) ->
      St1 = reverse(dropwhile(Skip, reverse(St0))),
      Print = fun (F) -> format_stackcall(F, Format) end,
      map(Print, St1).
  
  format_stackcall({M,F,A}, _) when is_integer(A) ->    %Pre R15
      lfe_io:format1("  in ~w:~w/~w\n", [M,F,A]);
  format_stackcall({M,F,A}, Format) ->
      ["  in ",Format([':',M,F|A], 5),"\n"];
  format_stackcall({M,F,A,Loc},_) when is_integer(A) -> %R15 and later.
      lfe_io:format1("  in ~w:~w/~w ~s\n", [M,F,A,location(Loc)]);
  format_stackcall({M,F,A,_}, Format) ->
      ["  in ",Format([':',M,F|A], 5),"\n"].
  
  location(Loc) ->
      File = proplists:get_value(file, Loc),
      Line = proplists:get_value(line, Loc),
      if File =/= undefined, Line =/= undefined ->
              lfe_io:format1("(~s, line ~w)", [File,Line]);
         true -> ""
      end.
  
  is_stacktrace([{M,F,A}|Fs])                     %Pre R15
    when is_atom(M), is_atom(F), is_integer(A) -> is_stacktrace(Fs);
  is_stacktrace([{M,F,As}|Fs])
    when is_atom(M), is_atom(F), length(As) >= 0 -> is_stacktrace(Fs);
  is_stacktrace([{M,F,A,I}|Fs])                   %R15 and later
    when is_atom(M), is_atom(F), is_integer(A), is_list(I) -> is_stacktrace(Fs);
  is_stacktrace([{M,F,As,I}|Fs])
    when is_atom(M), is_atom(F), length(As) >= 0, is_list(I) -> is_stacktrace(Fs);
  is_stacktrace([]) -> true;
  is_stacktrace(_) -> false.
  