// we are already visiting this vertex, this mean we have a cycle
                    int pos = cycle.lastIndexOf(v);
                    List<String> ret = cycle.subList(pos, cycle.size());
                    ret.add(v);
                    return ret;
                }
            }
        }
        return null;
    }

    assertEquals(Sets.<@Nullable String>newHashSet(null, "tree"), keySet.headSet("yahoo"));
    assertEquals(Sets.newHashSet("google"), keySet.tailSet("yahoo"));
    assertEquals(Sets.newHashSet("tree"), keySet.subSet("ask", "yahoo"));
  }

  @GwtIncompatible // SerializableTester
  public void testExplicitComparatorSerialization() {
    TreeMultimap<@Nullable String, @Nullable Integer> multimap = createPopulate();

    if (newFromIndex == 0 && newToIndex == size()) {
      return this;
    } else if (newFromIndex < newToIndex) {
      return new RegularImmutableSortedSet<>(
          elements.subList(newFromIndex, newToIndex), comparator);
    } else {
      return emptySet(comparator);
    }
  }

  @Override
  int indexOf(@CheckForNull Object target) {
    if (target == null) {
      return -1;

      reversedList = tmp;
    }
    while (reversedList != null) {
      executeListener(reversedList.runnable, reversedList.executor);
      reversedList = reversedList.next;
    }
  }

  /**
   * Submits the given runnable to the given {@link Executor} catching and logging all {@linkplain
   * RuntimeException runtime exceptions} thrown by the executor.
   */
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception

            } else if (state == DfsState.VISITING) {
                // we are already visiting this vertex, this mean we have a cycle
                int pos = cycle.lastIndexOf(v.label);
                List<String> ret = cycle.subList(pos, cycle.size());
                ret.add(v.label);
                return ret;
            }
        }
        return null;
    }

    static class Vertex {
        final String label;

          extras = new ArrayList<>();
        }
        extras.add(other.element);
        extras.addAll(other.extras);
        if (extras.size() > MAX_EXTRAS) {
          extras.subList(MAX_EXTRAS, extras.size()).clear();
          throw multiples(true);
        }
        return this;
      }
    }

    assertEquals(Sets.<@Nullable String>newHashSet(null, "tree"), keySet.headSet("yahoo"));
    assertEquals(Sets.newHashSet("google"), keySet.tailSet("yahoo"));
    assertEquals(Sets.newHashSet("tree"), keySet.subSet("ask", "yahoo"));
  }

  @GwtIncompatible // SerializableTester
  public void testExplicitComparatorSerialization() {
    TreeMultimap<@Nullable String, @Nullable Integer> multimap = createPopulate();