assertEqualCharNodes(traverser.breadthFirst(charactersOf("acdb")), "acdb");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("db")), "db");
  }

  @Test
  public void forGraph_breadthFirst_multiGraph() {
    Traverser<Character> traverser = Traverser.forGraph(MULTI_GRAPH);
    assertEqualCharNodes(traverser.breadthFirst('a'), "abcd");

    int dotIndex = fileName.lastIndexOf('.');
    return (dotIndex == -1) ? fileName : fileName.substring(0, dotIndex);
  }

  /**
   * Returns a {@link Traverser} instance for the file and directory tree. The returned traverser
   * starts from a {@link File} and will return all files and directories it encounters.
   *
   * <p><b>Warning:</b> {@code File} provides no support for symbolic links, and as such there is no

    int dotIndex = fileName.lastIndexOf('.');
    return (dotIndex == -1) ? fileName : fileName.substring(0, dotIndex);
  }

  /**
   * Returns a {@link Traverser} instance for the file and directory tree. The returned traverser
   * starts from a {@link File} and will return all files and directories it encounters.
   *
   * <p><b>Warning:</b> {@code File} provides no support for symbolic links, and as such there is no

   * multimap, and vice versa. The entries set does not support the {@code add} or {@code addAll}
   * operations.
   *
   * <p>The iterator generated by the returned set traverses the entries in the order they were
   * added to the multimap.
   *
   * <p>Each entry is an immutable snapshot of a key-value mapping in the multimap, taken at the

    return cycle(Lists.newArrayList(elements));
  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input

    return cycle(Lists.newArrayList(elements));
  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input

      return backingMap.isEmpty();
    }

    @Override
    public void clear() {
      backingMap.clear();
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>The set's iterator traverses the mappings for the first row, the mappings for the second
   * row, and so on.
   *
   * <p>Each cell is an immutable snapshot of a row key / column key / value mapping, taken at the

 *
 * <p>This class and its iterator implement all of the optional methods of the {@link
 * Collection} and {@link Iterator} interfaces. The Iterator provided in method {@link #iterator()}
 * is not guaranteed to traverse the elements of the MonitorBasedPriorityBlockingQueue in
 * any particular order. If you need ordered traversal, consider using {@code
 * Arrays.sort(pq.toArray())}. Also, method {@code drainTo} can be used to remove some or

        keyIterator.remove();
      }
      totalSize--;
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>The iterator generated by the returned collection traverses the values for one key, followed
   * by the values of a second key, and so on.
   */
  @Override
  public Collection<V> values() {
    return super.values();
  }

  @Override

   * at {@code node} and ending at {@code v}. This implementation includes {@code node} as the first
   * element in the result.
   *
   * <p>If needed, the {@link Traverser} class provides more flexible and lighter-weight ways to
   * list the nodes reachable from a given node or nodes. See the <a
   * href="https://github.com/google/guava/wiki/GraphsExplained#Graph-traversal">"Graph traversal"