static L<Concept> unrollOptions(Concept c) {
  if (c << Options)
    ret concatMap("unrollOptions", c/Options);
  if (!conceptHasOptions(c))
    ret ll(c);
  else { // c has Options hidden somewhere within - recurse & "multiply"
    new Map<S, O> simples;
    Map<S, L<Concept>> multiples = new TreeMap;
  
    for (S field : conceptFields(c)) {
      O val = cget(c, field);
      if (!val << Concept)
        simples.put(field, val);
      else {
        L<Concept> l = unrollOptions(val/Concept);
        if (empty(l)) ret ll();
        else if (l(l) == 1)
          simples.put(field, first(l));
        else
          multiples.put(field, l);
      }
    }
    
    final Concept d = unlisted(c.getClass());
    csetMap(d, simples);
    
    if (empty(multiples))
      ret ll(d);
    else {
      if (l(multiples) > 2) warn("todo johnny");
      new L out;
      L<S> fields = asList(keys(multiples));
      
      S field0 = fields.get(0);
      for (Concept value0 : multiples.get(field0)) {
        Concept e = unlisted(c.getClass());
        copyConceptFields(d, e);
        cset(e, field0, value0);
        if (l(multiples) == 1) out.add(e); else {
          S field1 = fields.get(1);
          for (Concept value1 : multiples.get(field1)) {
            Concept f = unlisted(c.getClass());
            copyConceptFields(e, f);
            cset(f, field1, value1);
            out.add(f);
          }
        }
      }
      ret out;
    }
  }
}