static <A, B> LPair<A, L<B>> multiMapToMapPairs(MultiMap<A, B> mm) {
  LPair<A, L<B>> out = new L;
  for (A key : keys(mm))
    out.add(pair(key, mm.get(key)));
  ret out;
}

static <A, B> LPair<A, Cl<B>> multiMapToMapPairs(IMultiMap<A, B> mm) {
  LPair<A, Cl<B>> out = new L;
  for (A key : keys(mm))
    out.add(pair(key, mm.get(key)));
  ret out;
}

Began life as a copy of #1020210