static Pair<guessDeepObjectSize_recursive_Data, Long> estimateWebBotSize(O o) {
  Collection<S> fields = fields(o);
  new L l;
  for (S field : fields) {
    if (sizeCalculation_shouldIgnoreProgramField(field)) continue;
    O value = get(o, field);
    if (value == null) continue;
    l.add(value);
  }
  
  O[] array = asObjectArray(l);
  new guessDeepObjectSize_recursive_Data data;
  data.seen.add(o);
  ret pair(data,
    guessDeepObjectSize_recursive(data, array)
      -inMemorySizeOfArray(array)
      +unsafe_sizeOf(o));
}