return subMap(
          Range.range(
              fromKey, BoundType.forBoolean(fromInclusive),
              toKey, BoundType.forBoolean(toInclusive)));
    }

    @Override
    public NavigableMap<Cut<C>, Range<C>> headMap(Cut<C> toKey, boolean inclusive) {
      return subMap(Range.upTo(toKey, BoundType.forBoolean(inclusive)));
    }

    @Override

      }
      return subSet(
          Range.range(
              fromElement, BoundType.forBoolean(fromInclusive),
              toElement, BoundType.forBoolean(toInclusive)));
    }

    @Override
    ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
      return subSet(Range.downTo(fromElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    public boolean contains(@Nullable Object o) {