public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
    return headMap(toKey, false);
  }

  @Override
  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
    return tailMap(fromKey, true);
  }

  @Override

  public ImmutableSortedMap<K, V> subMap(
      K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
    checkNotNull(fromKey);
    checkNotNull(toKey);
    checkArgument(
        comparator().compare(fromKey, toKey) <= 0,
        "expected fromKey <= toKey but %s > %s",
        fromKey,
        toKey);
    return headMap(toKey, toInclusive).tailMap(fromKey, fromInclusive);
  }

  /**

          && (upperBound == null || compare(upperBound, o) > 0);
    }

    @Override
    public SortedMap<C, V> subMap(C fromKey, C toKey) {
      checkArgument(rangeContains(checkNotNull(fromKey)) && rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, fromKey, toKey);
    }

    @Override
    public SortedMap<C, V> headMap(C toKey) {
      checkArgument(rangeContains(checkNotNull(toKey)));

      standardClear();
    }

    @Override
    public boolean isEmpty() {
      return standardIsEmpty();
    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      return standardSubMap(fromKey, toKey);
    }

    @Override
    public @Nullable Entry<K, V> lowerEntry(K key) {
      return standardLowerEntry(key);
    }

    @Override

    }

    @Override
    public SortedMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return transformEntries(fromMap().subMap(fromKey, toKey), transformer);
    }

    @Override
    public SortedMap<K, V2> tailMap(@ParametricNullness K fromKey) {
      return transformEntries(fromMap().tailMap(fromKey), transformer);
    }
  }

  @GwtIncompatible // NavigableMap

    }

    @Override
    public SortedMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return transformEntries(fromMap().subMap(fromKey, toKey), transformer);
    }

    @Override
    public SortedMap<K, V2> tailMap(@ParametricNullness K fromKey) {
      return transformEntries(fromMap().tailMap(fromKey), transformer);
    }
  }

  @GwtIncompatible // NavigableMap

    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      synchronized (mutex) {
        return sortedMap(delegate().subMap(fromKey, toKey), mutex);
      }
    }

    @Override
    public SortedMap<K, V> tailMap(K fromKey) {
      synchronized (mutex) {
        return sortedMap(delegate().tailMap(fromKey), mutex);
      }
    }

    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      synchronized (mutex) {
        return sortedMap(delegate().subMap(fromKey, toKey), mutex);
      }
    }

    @Override
    public SortedMap<K, V> tailMap(K fromKey) {
      synchronized (mutex) {
        return sortedMap(delegate().tailMap(fromKey), mutex);
      }
    }

    val adapter = Adapters.INTEGER_AS_LONG.asSequenceOf()
    assertThat(adapter.fromDer(bytes)).isEqualTo(sequenceOf)
    assertThat(adapter.toDer(sequenceOf)).isEqualTo(bytes)
  }

  @Test fun `point with only x set`() {
    val bytes = "3003800109".decodeHex()
    val point = Point(9L, null)
    assertThat(Point.ADAPTER.fromDer(bytes)).isEqualTo(point)
    assertThat(Point.ADAPTER.toDer(point)).isEqualTo(bytes)
  }

   *
   * If there's nothing to read and no default value, this will throw an exception.
   */
  fun fromDer(reader: DerReader): T

  fun fromDer(byteString: ByteString): T {
    val buffer = Buffer().write(byteString)
    val reader = DerReader(buffer)
    return fromDer(reader)
  }

  /**
   * Writes [value] to this adapter, unless it is the default value and can be safely omitted.
   *