code: public void putAll(IntIntMultiMap m) {
          // REMINDER: if IntIntMultiMap is every updated with a primitive based
          // EntrySet, use that
          IntIterator keys = m.keySet().iterator();
          while (keys.hasNext()) {
              int key = keys.nextInt();
              IntSet values = m.get(key);
              putMany(key, values);
          }
      }
docs: {@inheritDoc}