anchor.diff:                         is_tuple(hd(Measure)) andalso size(hd(Measure)) == 2 ->
       #tscell{map_value = Measure};
   cell_for(Measure) when is_list(Measure) ->
  -    #tscell{set_value = Measure}.
  +    #tscell{set_value = Measure};
  +cell_for(undefined) ->
  +    #tscell{}.
   
   -spec decode_rows([#tsrow{}]) -> [tsrow()].
   decode_rows(Rows) ->
  
positive.code:                       timestamp_value = undefined,
                        boolean_value   = undefined,
                        set_value       = Set,
                        map_value       = undefined} | T], Acc) ->
      decode_cells(T, [Set | Acc]);
  decode_cells([#tscell{binary_value    = undefined,
                        integer_value   = undefined,
  
negative.code:                       timestamp_value = undefined,
                        boolean_value   = undefined,
                        set_value       = [],
                        map_value       = Map} | T], Acc)
    when is_binary(Map) ->
      decode_cells(T, [Map | Acc]);
  decode_cells([#tscell{binary_value    = undefined,
                        integer_value    = undefined,
                        numeric_value    = undefined,
                        timestamp_value  = undefined,
                        boolean_value    = undefined,
                        set_value        = [],
                        map_value        = undefined} | T], Acc) ->
      decode_cells(T, [undefined | Acc]).
  