anchor.diff:  escape_value_check(V) when is_boolean(V) -> V;
   escape_value_check(V) when is_number(V) -> V;
   escape_value_check(V) when is_atom(V) ->
  -    escape_check( atom_to_binary(V, utf8) );
  +    V1 = atom_to_binary(V, utf8),
  +    case escape_check(V1) of
  +        V1 -> V;
  +        _ -> undefined
  +    end;
   escape_value_check({trans, _Ts} = Tr) ->
       escape_check(Tr);
   escape_value_check(V) when is_list(V) ->
  
positive.code: escape_value(V) when is_boolean(V) -> V;
  escape_value(V) when is_number(V) -> V;
  escape_value(V) when is_atom(V) ->
      escape( atom_to_binary(V, utf8) );
  escape_value({trans, _Ts} = Tr) ->
      escape(Tr);
  escape_value(V) when is_list(V) ->
  
negative.code: escape_props1(_K, V, _Options) when is_number(V); is_boolean(V) ->
      V;
  escape_props1(K, V, Options) when is_atom(V) ->
      V1 = atom_to_binary(V, utf8),
      case escape_props1(K, V1, Options) of
          V1 -> V;
          _ -> undefined
      end;
  escape_props1(<<"body", _/binary>>, V, Options) ->
      sanitize(V, Options);
  escape_props1(<<"summary">>, Summary, _Options) ->
  