*
   * <p>The default value is {@link ElementOrder#insertion() insertion order}.
   */
  public <N1 extends N> ValueGraphBuilder<N1, V> nodeOrder(ElementOrder<N1> nodeOrder) {
    ValueGraphBuilder<N1, V> newBuilder = cast();
    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  /**

    assertThat(graphAsMutableGraph.removeEdge(N1, N3)).isTrue();
    assertThat(graph.adjacentNodes(N1)).containsExactly(N2, N4);
  }

  @Test
  public void removeEdge_nodeNotPresent() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    assertThat(graphAsMutableGraph.removeEdge(N1, NODE_NOT_IN_GRAPH)).isFalse();
    assertThat(graph.successors(N1)).contains(N2);
  }

  @Test

  public void testFirstNonNull_withNonNull() {
    String s1 = "foo";
    String s2 = MoreObjects.firstNonNull(s1, "bar");
    assertSame(s1, s2);

    Long n1 = 42L;
    Long n2 = MoreObjects.firstNonNull(null, n1);
    assertSame(n1, n2);

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);
    assertSame(b1, b2);
  }

  public void testFirstNonNull_throwsNullPointerException() {

  public void testFirstNonNull_withNonNull() {
    String s1 = "foo";
    String s2 = MoreObjects.firstNonNull(s1, "bar");
    assertSame(s1, s2);

    Long n1 = 42L;
    Long n2 = MoreObjects.firstNonNull(null, n1);
    assertSame(n1, n2);

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);
    assertSame(b1, b2);
  }

  public void testFirstNonNull_throwsNullPointerException() {

    addEdge(N1, N1, E11);
    assertThat(network.successors(N1)).containsExactly(N1);
    addEdge(N2, N1, E12);
    assertThat(network.successors(N1)).containsExactly(N1, N2);
  }

  @Test
  public void degree_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.degree(N1)).isEqualTo(2);
    addEdge(N1, N2, E12);
    assertThat(network.degree(N1)).isEqualTo(3);

    directedGraph.putEdgeValue(N1, N1, E11);
    directedGraph.putEdgeValue(N3, N4, E34);

    MutableValueGraph<Integer, String> expectedTranspose =
        ValueGraphBuilder.directed().allowsSelfLoops(true).build();
    expectedTranspose.putEdgeValue(N3, N1, E13);
    expectedTranspose.putEdgeValue(N1, N3, E31);
    expectedTranspose.putEdgeValue(N2, N1, E12);
    expectedTranspose.putEdgeValue(N1, N1, E11);

    assertThat(graphAsMutableGraph.removeEdge(N1, N3)).isTrue();
    assertThat(graph.adjacentNodes(N1)).containsExactly(N2, N4);
  }

  @Test
  public void removeEdge_nodeNotPresent() {
    assume().that(graphIsMutable()).isTrue();

    putEdge(N1, N2);
    assertThat(graphAsMutableGraph.removeEdge(N1, NODE_NOT_IN_GRAPH)).isFalse();
    assertThat(graph.successors(N1)).contains(N2);
  }

  @Test

  public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() {
    return new StandardMutableNetwork<>(this);
  }

  @SuppressWarnings("unchecked")
  private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() {
    return (NetworkBuilder<N1, E1>) this;
  }

if ! command -v xargs >/dev/null 2>&1
then
    die "xargs is not available"
fi

# Use "xargs" to parse quoted args.
#
# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
#
# In Bash we could simply go:
#
#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
#   set -- "${ARGS[@]}" "$@"
#
# but POSIX shell has neither arrays nor command substitution, so instead we

    }
  }

  public <N1 extends Number, N2 extends Number, N11 extends N1>
      void testisSupertypeOf_typeVariable() {
    assertAssignable(
        TypeToken.of(new TypeCapture<N1>() {}.capture()),
        TypeToken.of(new TypeCapture<N1>() {}.capture()));
    assertNotAssignable(new TypeToken<List<N11>>() {}, new TypeToken<List<N1>>() {});
    assertNotAssignable(