anchor.diff:          atom -> {atom, erl_syntax:atom_value(Node)};
           _    -> non_atom
       end.
  +
  +with_increased_backtrace_depth(Fun) ->
  +    %% The backtrace_depth is quite often too short,
  +    %% when things go wrong inside the parse transform,
  +    %% or during the runtime application of additional transforms.
  +    %%
  +    %% The backtrace_depth controls how many levels of stack
  +    %% to include in the crash, too few levels means we only
  +    %% see the innermost function calls, not the originating
  +    %% top-level calls, making it difficult to debug errors.
  +    %%
  +    %% So: up it (temporarily).
  +    %%
  +    %% It is 8 in current Erlang/OTPs, but take some precautions
  +    %% in case it gets increased or changed in future versions.
  +    New = 32,
  +    try erlang:system_flag(backtrace_depth, New) of
  +        Old when Old < New ->
  +            try Fun()
  +            after erlang:system_flag(backtrace_depth, Old)
  +            end;
  +        Old when Old == New ->
  +            Fun();
  +        Old when Old > New ->
  +            %% Don't decrease it!
  +            erlang:system_flag(backtrace_depth, Old),
  +            Fun()
  +    catch error:badarg -> %% Not available
  +            Fun()
  +    end.
  
positive.code: 
  %%@hidden
  runtime_expr_transform(ExprParseTree, Transforms) ->
      erl_syntax:revert(
        erl_syntax:copy_pos(
          ExprParseTree,
          apply_transforms(ExprParseTree, Transforms))).
  
  %%@hidden
  runtime_exprs_transform(ExprParseTrees, Transforms) ->
      [erl_syntax:revert(
         erl_syntax:copy_pos(
           ExprParseTree,
           apply_transforms(ExprParseTree, Transforms)))
       || ExprParseTree <- ExprParseTrees].
  
  apply_transforms(ParseTree, Transforms) ->
      lists:foldl(fun apply_transform/2, ParseTree, Transforms).
  
negative.code: 
  %%@hidden
  erl_prettypr_format_nl(Form) ->
      with_increased_backtrace_depth(
        fun() -> [erl_prettypr:format(Form), "\n"] end).
  
  %%@hidden
  runtime_fn_transform(FnName, FnParseTree) ->
  