* b)} is true if and only if {@code equivalence.equivalent(function.apply(a), function.apply(b))}
   * is true.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Equivalence<Person> SAME_AGE = Equivalence.equals().onResultOf(GET_PERSON_AGE);
   * }</pre>
   *
   * <p>{@code function} will never be invoked with a null value.
   *
   * <p>Note that {@code function} must be consistent according to {@code this} equivalence

   * b)} is true if and only if {@code equivalence.equivalent(function.apply(a), function.apply(b))}
   * is true.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Equivalence<Person> SAME_AGE = Equivalence.equals().onResultOf(GET_PERSON_AGE);
   * }</pre>
   *
   * <p>{@code function} will never be invoked with a null value.
   *
   * <p>Note that {@code function} must be consistent according to {@code this} equivalence

  public static final String ACCESS_CONTROL_EXPOSE_HEADERS = "Access-Control-Expose-Headers";
  /** The HTTP {@code Access-Control-Max-Age} header field name. */
  public static final String ACCESS_CONTROL_MAX_AGE = "Access-Control-Max-Age";
  /** The HTTP {@code Age} header field name. */
  public static final String AGE = "Age";
  /** The HTTP {@code Allow} header field name. */
  public static final String ALLOW = "Allow";

    assertEqualCharNodes(traverser.breadthFirst(charactersOf("h")), "hdegabcf");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("gd")), "gdfabc");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("age")), "agef");
  }

  @Test
  public void forTree_breadthFirst_cyclicGraphContainingTree() throws Exception {
    Traverser<Character> traverser = Traverser.forTree(CYCLIC_GRAPH_CONTAINING_TREE);

different.  But if I'm not the same, the next question is, Who in
the world am I?  Ah, THAT'S the great puzzle!'  And she began
thinking over all the children she knew that were of the same age
as herself, to see if she could have been changed for any of
them.

  `I'm sure I'm not Ada,' she said, `for her hair goes in such
long ringlets, and mine doesn't go in ringlets at all; and I'm

    assertEqualCharNodes(traverser.breadthFirst(charactersOf("h")), "hdegabcf");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("gd")), "gdfabc");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("age")), "agef");
  }

  @Test
  public void forTree_breadthFirst_cyclicGraphContainingTree() throws Exception {
    Traverser<Character> traverser = Traverser.forTree(CYCLIC_GRAPH_CONTAINING_TREE);

different.  But if I'm not the same, the next question is, Who in
the world am I?  Ah, THAT'S the great puzzle!'  And she began
thinking over all the children she knew that were of the same age
as herself, to see if she could have been changed for any of
them.

  `I'm sure I'm not Ada,' she said, `for her hair goes in such
long ringlets, and mine doesn't go in ringlets at all; and I'm