* properties remain intact, and further updates to {@code graph} will be reflected in the view.
   */
  public static <N> Graph<N> transpose(Graph<N> graph) {
    if (!graph.isDirected()) {
      return graph; // the transpose of an undirected graph is an identical graph
    }

    if (graph instanceof TransposedGraph) {
      return ((TransposedGraph<N>) graph).graph;

   * properties remain intact, and further updates to {@code graph} will be reflected in the view.
   */
  public static <N> Graph<N> transpose(Graph<N> graph) {
    if (!graph.isDirected()) {
      return graph; // the transpose of an undirected graph is an identical graph
    }

    if (graph instanceof TransposedGraph) {
      return ((TransposedGraph<N>) graph).graph;

 * "Choosing the right graph type"</a> section of the Guava User Guide for more details.
 *
 * <h3>Capabilities</h3>
 *
 * <p>{@code Network} supports the following use cases (<a
 * href="https://github.com/google/guava/wiki/GraphsExplained#definitions">definitions of
 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow parallel edges

 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.graph.Graphs.copyOf;
import static com.google.common.graph.Graphs.inducedSubgraph;
import static com.google.common.graph.Graphs.reachableNodes;
import static com.google.common.graph.Graphs.transitiveClosure;
import static com.google.common.graph.Graphs.transpose;
import static com.google.common.truth.Truth.assertThat;

 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.graph.GraphConstants.INNER_CAPACITY;
import static com.google.common.graph.GraphConstants.INNER_LOAD_FACTOR;

 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.graph.TestUtil.assertEdgeNotInGraphErrorMessage;
import static com.google.common.graph.TestUtil.assertEdgeRemovedFromGraphErrorMessage;
import static com.google.common.graph.TestUtil.assertNodeNotInGraphErrorMessage;
import static com.google.common.graph.TestUtil.assertNodeRemovedFromGraphErrorMessage;

    graph.putEdge("a", "b");

    Traverser.forTree(graph); // Does not throw
  }

  @Test
  public void forTree_withUndirectedGraph_throws() throws Exception {
    MutableGraph<String> graph = GraphBuilder.undirected().build();
    graph.putEdge("a", "b");

    assertThrows(IllegalArgumentException.class, () -> Traverser.forTree(graph));
  }

  @Test
  @SuppressWarnings("CheckReturnValue")

    graph.putEdge("a", "b");

    Traverser.forTree(graph); // Does not throw
  }

  @Test
  public void forTree_withUndirectedGraph_throws() throws Exception {
    MutableGraph<String> graph = GraphBuilder.undirected().build();
    graph.putEdge("a", "b");

    assertThrows(IllegalArgumentException.class, () -> Traverser.forTree(graph));
  }

  @Test
  @SuppressWarnings("CheckReturnValue")

   * <a href="https://en.wikipedia.org/wiki/RDF/XML">RDF/XML</a> documents, which are XML
   * serializations of <a
   * href="https://en.wikipedia.org/wiki/Resource_Description_Framework">Resource Description
   * Framework</a> graphs.
   *
   * @since 14.0
   */
  public static final MediaType RDF_XML_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "rdf+xml");

  public static final MediaType RTF_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "rtf");

   * <a href="https://en.wikipedia.org/wiki/RDF/XML">RDF/XML</a> documents, which are XML
   * serializations of <a
   * href="https://en.wikipedia.org/wiki/Resource_Description_Framework">Resource Description
   * Framework</a> graphs.
   *
   * @since 14.0
   */
  public static final MediaType RDF_XML_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "rdf+xml");

  public static final MediaType RTF_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "rtf");