anchor.diff:  
   -spec pretty_from_box([#box{}] | #box{}) -> binary().
   pretty_from_box([]) -> [];
  -pretty_from_box(#box{collapsed=true}=Box) -> flat_from_box(Box);
   pretty_from_box(#box{name= <<>>,children=[]}) -> <<>>;
   pretty_from_box(#box{ind=Ind,name=Name,children=[]}) ->
       iolist_to_binary([indent(Ind), Name, "\r\n"]);
  
positive.code: 
  -ifdef(DefCollInd).
  -undef(DefCollInd).
  -define(DefCollInd,10).
  -endif.
  
  %% TESTS ------------------------------------------------------------------
  
negative.code: foldb(_, _P, {'hierarchical query', {}}) -> empty;
  
  foldb(Ind, _P, T) when is_binary(T); is_atom(T) -> mk_box(Ind, [], T);
  foldb(Ind, _P, {param, T}) -> mk_box(Ind-1, [], T);
  
  %%TODO: Improve these ugly nested cases to check for errors.
  foldb(Ind, P, {'as', {'fun',Fun,List}, Alias}) ->
  