* key of {@link #belowSamplesLesser()}.
   */
  Entry<K, V> belowSamplesGreater();

  /**
   * Returns an entry with a key greater than the keys of the {@link #samples()} but less than the
   * key of {@link #aboveSamplesGreater()}.
   */
  Entry<K, V> aboveSamplesLesser();

  /**

    while (lines.peek() == null) {
      Java8Compatibility.clear(cbuf);
      // The default implementation of Reader#read(CharBuffer) allocates a
      // temporary char[], so we call Reader#read(char[], int, int) instead.
      int read = (reader != null) ? reader.read(buf, 0, buf.length) : readable.read(cbuf);
      if (read == -1) {
        lineBuf.finish();
        break;
      }

  }

  @Override
  public int compare(@CheckForNull T left, @CheckForNull T right) {
    if (left == right) {
      return 0;
    }
    if (left == null) {
      return LEFT_IS_GREATER;
    }
    if (right == null) {
      return RIGHT_IS_GREATER;
    }
    return ordering.compare(left, right);
  }

  @Override
  @SuppressWarnings("nullness") // should be safe, but not sure if we can avoid the warning

    BufferedReader reader = source.openBufferedStream();
    assertTrue(source.wasStreamOpened());
    assertFalse(source.wasStreamClosed());

    StringWriter writer = new StringWriter();
    char[] buf = new char[64];
    int read;
    while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    return new Range<>(lowerBound, upperBound);
  }

  /**
   * Returns a range that contains all values strictly greater than {@code lower} and strictly less
   * than {@code upper}.
   *
   * @throws IllegalArgumentException if {@code lower} is greater than <i>or equal to</i> {@code
   *     upper}
   * @throws ClassCastException if {@code lower} and {@code upper} are not mutually comparable

      assertTrue(t.equals(t));

      for (int j = i + 1; j < valuesInExpectedOrder.size(); j++) {
        T greater = valuesInExpectedOrder.get(j);
        assertTrue(greater + ".compareTo(" + t + ')', greater.compareTo(t) > 0);
        assertFalse(greater.equals(t));
      }
    }
  }

  /**
   * Returns a collection that simulates concurrent modification by having its size method return

    sink.write(STRING);

    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());
    assertEquals(STRING, sink.getString());
  }

  public void testWriteFrom_reader() throws IOException {
    StringReader reader = new StringReader(STRING);
    sink.writeFrom(reader);

    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());
    assertEquals(STRING, sink.getString());
  }

   *
   * @param value any value in the range of the {@code byte} type
   * @return the {@code byte} value that equals {@code value}
   * @throws IllegalArgumentException if {@code value} is greater than {@link Byte#MAX_VALUE} or
   *     less than {@link Byte#MIN_VALUE}
   */
  public static byte checkedCast(long value) {
    byte result = (byte) value;
    checkArgument(result == value, "Out of range: %s", value);

    }

    @Override
    public String getSinkContents() throws IOException {
      File file = getFile();
      Reader reader = new InputStreamReader(new FileInputStream(file), Charsets.UTF_8);
      StringBuilder builder = new StringBuilder();
      CharBuffer buffer = CharBuffer.allocate(100);
      while (reader.read(buffer) != -1) {
        Java8Compatibility.flip(buffer);
        builder.append(buffer);

   */
  public double populationCovariance() {
    checkState(count() != 0);
    return sumOfProductsOfDeltas / count();
  }

  /**
   * Returns the sample covariance of the values. The count must be greater than one.
   *
   * <p>This is not guaranteed to return zero when the dataset consists of the same pair of values
   * multiple times, due to numerical errors.
   *
   * <h3>Non-finite values</h3>
   *