static <A, B, C> void doubleKeyedMapPutVerbose(S mapName, DoubleKeyedMap<A, B, C> map, A key1, B key2, C value) {
  if (map != null && key1 != null && key2 != null && value != null) {
    C old = map.put(key1, key2, value);
    if (!eq(value, old))
      print((old == null ? "Adding to" : "Updating") + " \*mapName*/: \*key1*/, \*key2*/ => \*value*/");
  }
}

Began life as a copy of #1027781