public static ValueGraphBuilder<Object, Object> undirected() {
    return new ValueGraphBuilder<>(false);
  }

  /**
   * Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code
   * graph}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link ValueGraph}
   * interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link

  public static NetworkBuilder<Object, Object> undirected() {
    return new NetworkBuilder<>(false);
  }

  /**
   * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code
   * network}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
   * such as {@link Network#isDirected()}. Other properties, such as {@link