////////////////////////////////////////////////////////////////////////////////

  CCTK_VINFO("ScheduleTraverseGH");

  CCTK_VINFO("ScheduleTraverseGH [%d] %s", cctkGH->cctk_iteration, where);

  CCTK_VINFO("CallFunction");

  assert(function);
  assert(attribute);
  assert(data);
  cGH *restrict const cctkGH = static_cast<cGH *>(data);

  int didsync = CCTK_CallFunction(function, attribute, data);

  CCTK_VINFO("CallFunction [%d] %s: %s::%s", cctkGH->cctk_iteration,
             attribute->where, attribute->thorn, attribute->routine);
  // Decode mode
  enum class mode_t { unknown, local, level, global, meta };
  const auto decode_mode = [&]() {
    bool local_mode = attribute->local;
    bool level_mode = attribute->level;
    bool global_mode = attribute->global;
    bool meta_mode = attribute->meta;
    assert(int(local_mode) + int(level_mode) + int(global_mode) +
               int(meta_mode) <=
           1);
    if (attribute->local)
      return mode_t::local;
    if (attribute->level)
      return mode_t::level;
    if (attribute->global)
      return mode_t::global;
    if (attribute->meta)
      return mode_t::meta;
    return mode_t::local; // default
  };
  const mode_t mode = decode_mode();
  switch (mode) {
  case mode_t::local: {
    // Call function once per tile
    CCTK_CallFunction(function, attribute, data);
    break;
  }
  case mode_t::level:
  case mode_t::global:
  case mode_t::meta: {
    // Call function once
#warning "not yet implemented"
    assert(0);
    CCTK_CallFunction(function, attribute, data);
    break;
  }
  default:
    assert(0);
  }
  int didsync = 1;