anchor.diff:      to_binary_nif(Element, Pretty);
   to_iolist([Element], Pretty) ->
       to_iolist(Element, Pretty);
  -to_iolist([_ | _] = Elements, Pretty) ->
  -    Head = hd(Elements),
  +to_iolist([Head | _] = Elements, Pretty) ->
       [Last | RevChildren] = lists:reverse(tl(Elements)),
       case {Head, Last} of
           {#xmlstreamstart{name = Name, attrs = Attrs},
  
positive.code:          xml_size/1,
           xml_sort/1,
           to_pretty_iolist/1]).
  
  -export([]).
  
  -export_type([attr/0,
                cdata/0,
  
negative.code: -spec xml_sort(item() | [item()]) -> item() | [item()].
  xml_sort(#xmlcdata{} = Cdata) ->
      Cdata;
  xml_sort(#xmlel{ attrs = Attrs, children = Children } = El) ->
      El#xmlel{
        attrs = lists:sort(Attrs),
        children = [ xml_sort(C) || C <- Children ]
  