expectAddFailure(sortedMultiset.headMultiset(b.getElement(), OPEN), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), CLOSED), c);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), CLOSED), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), c);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), a);
  }

    expectAddFailure(sortedMultiset.headMultiset(b.getElement(), OPEN), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), CLOSED), c);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), CLOSED), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), c);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), b);
    expectAddFailure(sortedMultiset.headMultiset(a.getElement(), OPEN), a);
  }

    assertEquals(Integer.MAX_VALUE, ms.count("b"));
    assertEquals(3, ms.count("c"));

    assertEquals(Integer.MAX_VALUE, ms.headMultiset("c", CLOSED).size());
    assertEquals(Integer.MAX_VALUE, ms.headMultiset("b", CLOSED).size());
    assertEquals(Integer.MAX_VALUE, ms.headMultiset("a", CLOSED).size());

    assertEquals(3, ms.tailMultiset("c", CLOSED).size());

                }

                if (to == Bound.INCLUSIVE) {
                  multiset = multiset.headMultiset(lastInclusive, BoundType.CLOSED);
                } else if (to == Bound.EXCLUSIVE) {
                  multiset = multiset.headMultiset(lastExclusive, BoundType.OPEN);
                }

                return multiset;
              }
            })

  public final @Nullable Entry<E> pollLastEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public abstract ImmutableSortedMultiset<E> headMultiset(E upperBound, BoundType boundType);

  @Override
  public ImmutableSortedMultiset<E> subMultiset(
      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
    checkArgument(

        prevEntry = null;
      }
    };
  }

  @Override
  public Iterator<E> iterator() {
    return Multisets.iteratorImpl(this);
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
    return new TreeMultiset<>(
        rootReference,
        range.intersect(GeneralRange.upTo(comparator(), upperBound, boundType)),
        header);
  }