static Map ciMapFromKeyAndValueField(Collection l, S keyField, S valueField) {
  Map map = ciMap();
  for (O o : l)
    mapPut(map, getOpt(o, keyField), getOpt(o, valueField));
  ret map;
}

static Map ciMapFromKeyAndValueField(S keyField, S valueField, Collection l) {
  ret ciMapFromKeyAndValueField(l, keyField, valueField);
}