Read the sensor proximity and return it as an unsigned 16-bit value.
        The larger the value the closer an object is to the sensor.

def read_proximity(self, timeout_sec=1):
        """Read the sensor proximity and return it as an unsigned 16-bit value.
        The larger the value the closer an object is to the sensor.
        """
        # Ask for a proximity measurement and wait for the response.
        self._device.write8(VCNL40xx_COMMAND, VCNL40xx_MEASUREPROXIMITY)
        self._wait_response(VCNL40xx_PROXIMITYREADY, timeout_sec)
        # Return the proximity response.
        return self._device.readU16BE(VCNL40xx_PROXIMITYDATA)