code: public static <R, C, V> ArrayTable<R, C, V> create(
        Iterable<? extends R> rowKeys, Iterable<? extends C> columnKeys) {
      return new ArrayTable<R, C, V>(rowKeys, columnKeys);
    }
docs: Creates an empty {@code ArrayTable}.
  
  @param rowKeys row keys that may be stored in the generated table
  @param columnKeys column keys that may be stored in the generated table
  @throws NullPointerException if any of the provided keys is null
  @throws IllegalArgumentException if {@code rowKeys} or {@code columnKeys}
  contains duplicates or is empty