for (int vi = 0; vi < groupdata.numvars; ++vi)
            assert(groupdata.valid.at(tl).at(vi).valid_int);

          bool all_valid = true;
          for (int vi = 0; vi < groupdata.numvars; ++vi) {
            if(!groupdata.valid.at(tl).at(vi).valid_int) {
              CCTK_VWARN(CCTK_WARN_ALERT,
                         "Grid function '%s' interior not valid before restrict",
                         CCTK_FullVarName(vi));
              all_valid = false;
            }
          }
          if (!all_valid) {
            CCTK_ERROR("Found grid functions that are not valid in the interior");
          }