static <A extends Concept> A nuLike findConceptWhereCI(Class<A> c, O... params) {
  ret findConceptWhereCI(db_mainConcepts(), c, params);
}

static <A extends Concept> A findConceptWhereCI(Concepts concepts, Class<A> c, O... params) {
  params = expandParams(c, params);
  
  // find smallest index to use
  new Lowest<IF0<Cl<A>>> bestIndex;
  
  if (concepts.ciFieldIndices != null)
    for ping (int i = 0; i < l(params); i += 2) {
      O val = params[i+1];
      IFieldIndex<A, O> index = concepts.getCIFieldIndex(c, (S) params[i]);
      if (index != null) {
        Cl<A> l = index.getAll(val);
        bestIndex.put(() -> l, l(l));
      }
      if (concepts.useBackRefsForSearches && val instanceof Concept) {
        // conservatively use full ref count as score until we store backRefs by class
        bestIndex.put(() -> findBackRefs(val/Concept, c), val/Concept._backRefCount());
      }
    }
  
  ifdef findConceptWhereCI_debug
    print("findConceptWhereCI bestIndex count=" + bestIndex.score());
  endifdef
  if (bestIndex.has()) {
    Cl<A> l = bestIndex!!;
    if (l(params) == 2) ret first(l); // nothing to filter, index should suffice
    for ping (A x : l)
      if (checkConceptFieldsIC(x, params)) ret x;
    null;
  } else {
    // table scan
    for ping (A x : concepts.list(c))
      if (checkConceptFieldsIC(x, params)) ret x;
    null;
  }
}

static Concept findConceptWhereCI(Concepts concepts, S c, O... params) {
  for ping (Concept x : concepts.list(c))
    if (checkConceptFieldsIC(x, params)) ret x;
  null;
}