* versions.
   */
  public byte[] toByteArray() {
    ByteBuffer buffer = ByteBuffer.allocate(BYTES).order(ByteOrder.LITTLE_ENDIAN);
    xStats.writeTo(buffer);
    yStats.writeTo(buffer);
    buffer.putDouble(sumOfProductsOfDeltas);
    return buffer.array();
  }

  /**
   * Creates a {@link PairedStats} instance from the given byte representation which was obtained by
   * {@link #toByteArray}.
   *

    Hasher hasher = HASH_FN.newHasher();
    hasher.putFloat(0x01000101f).putFloat(0f);
    assertEquals(0x96a4f8cc6ecbf16L, hasher.hash().asLong());

    hasher = HASH_FN.newHasher();
    hasher.putDouble(0x0000000001000101d);
    assertEquals(0xcf54171253fdc198L, hasher.hash().asLong());
  }

  /** Convenience method to compute a fingerprint on a full bytes array. */
  private static long fingerprint(byte[] bytes) {

    HashCode unused = sink.hash();
    sink.assertInvariants(4);
    sink.assertBytes(new byte[] {1, 2, 3, 4});
  }

  public void testDouble() {
    Sink sink = new Sink(8);
    sink.putDouble(Double.longBitsToDouble(0x0807060504030201L));
    HashCode unused = sink.hash();
    sink.assertInvariants(8);
    sink.assertBytes(new byte[] {1, 2, 3, 4, 5, 6, 7, 8});
  }

   * versions.
   */
  public byte[] toByteArray() {
    ByteBuffer buffer = ByteBuffer.allocate(BYTES).order(ByteOrder.LITTLE_ENDIAN);
    xStats.writeTo(buffer);
    yStats.writeTo(buffer);
    buffer.putDouble(sumOfProductsOfDeltas);
    return buffer.array();
  }

  /**
   * Creates a {@link PairedStats} instance from the given byte representation which was obtained by
   * {@link #toByteArray}.
   *

          sink.putFloat(value);
        }
      }
    },
    PUT_DOUBLE() {
      @Override
      void performAction(Random random, Iterable<? extends PrimitiveSink> sinks) {
        double value = random.nextDouble();
        for (PrimitiveSink sink : sinks) {
          sink.putDouble(value);
        }
      }
    },
    PUT_BYTES() {
      @Override