STRING out_plotfile_groups "Groups to output as AMReX plotfile" STEERABLE=always
{
  ".*" :: ""
} ""

  for (int gi = 0; gi < numgroups; ++gi) {
    cGroup group;
    int ierr = CCTK_GroupData(gi, &group);
    assert(!ierr);

  vector<bool> group_enabled(numgroups, false);
  auto enable_group{[](int index, const char *optstring, void *callback) {
    vector<bool> &group_enabled = *static_cast<vector<bool> *>(callback);
    group_enabled.at(index) = true;
  }};
  CCTK_TraverseString(out_plotfile_groups, enable_group, &group_enabled,
                      CCTK_GROUP);

    if (group.grouptype != CCTK_GF)

  for (int gi = 0; gi < numgroups; ++gi) {
    if (!group_enabled.at(gi))
      continue;
    if (CCTK_GroupTypeI(gi) != CCTK_GF)