* @throws NumberFormatException if the value cannot be parsed as a Double
     */
    public static Double getDouble(final Map<String, Object> map, final String key) {
        return getDouble(map, key, null);
    }

    /**
     * Gets a Double value from the map with a default value.
     *
     * @param map The source map

        map.put("string", "3.5");

        assertEquals(1.5d, MapValueExtractor.getDouble(map, "double"), 0.001d);
        assertEquals(2.5d, MapValueExtractor.getDouble(map, "float"), 0.001d);
        assertEquals(3.5d, MapValueExtractor.getDouble(map, "string"), 0.001d);
        assertNull(MapValueExtractor.getDouble(map, "missing"));
    }

    @Test
    public void testGetBoolean() {

        BYTES,
        buffer.remaining());
    return new Stats(
        buffer.getLong(),
        buffer.getDouble(),
        buffer.getDouble(),
        buffer.getDouble(),
        buffer.getDouble());
  }

  private static final long serialVersionUID = 0;

    ByteBuffer buffer = ByteBuffer.wrap(byteArray).order(ByteOrder.LITTLE_ENDIAN);
    Stats xStats = Stats.readFrom(buffer);
    Stats yStats = Stats.readFrom(buffer);
    double sumOfProductsOfDeltas = buffer.getDouble();
    return new PairedStats(xStats, yStats, sumOfProductsOfDeltas);
  }

  private static final long serialVersionUID = 0;