anchor.diff:          {Op, Fun} ->
               Fun;
           false ->
  -            throw({update_operator_not_supported, Op})
  +            ?MANGO_ERROR({update_operator_not_supported, Op})
       end;
   update_operator_fun(_) ->
       undefined.
  
positive.code:     Props;
  do_update_inc(Props, [{Field, Incr} | Rest]) ->
      if is_number(Incr) -> ok; true ->
          throw({invalid_increment, Incr})
      end,
      NewProps = case get_field(Props, Field, fun is_number/1) of
          Value when is_number(Value) ->
  
negative.code: 
  
  -include_lib("couch/include/couch_db.hrl").
  -include("mango.hrl").
  
  
  from_bson({Props}) ->
  