def target_location(self,roi):
        """
        Point the gimbal at a specific region of interest (ROI).

        .. code-block:: python

            #Set the camera to track the current home location.
            vehicle.gimbal.target_location(vehicle.home_location)

        The target position must be defined in a :py:class:`LocationGlobalRelative` or :py:class:`LocationGlobal`.

        This function can be called in AUTO or GUIDED mode.

        In order to clear an ROI you can send a location with all zeros (e.g. ``LocationGlobalRelative(0,0,0)``).

        :param roi: Target location in global relative frame.
        """
        #set gimbal to targeting mode
        msg = self._vehicle.message_factory.mount_configure_encode(
                    0, 1,    # target system, target component
                    mavutil.mavlink.MAV_MOUNT_MODE_GPS_POINT,  #mount_mode
                    1,  # stabilize roll
                    1,  # stabilize pitch
                    1,  # stabilize yaw
                    )
        self._vehicle.send_mavlink(msg)

        #Get altitude relative to home irrespective of Location object passed in.
        if isinstance(roi, LocationGlobalRelative):
            alt = roi.alt
        elif isinstance(roi, LocationGlobal):
            if not self.home_location:
                self.commands.download()
                self.commands.wait_ready()
            alt = self.home_location.alt - roi.alt
        else:
            raise APIException('Expecting location to be LocationGlobal or LocationGlobalRelative.')

        #set the ROI
        msg = self._vehicle.message_factory.command_long_encode(
                    0, 1,    # target system, target component
                    mavutil.mavlink.MAV_CMD_DO_SET_ROI, #command
                    0, #confirmation
                    0, 0, 0, 0, #params 1-4
                    roi.lat,
                    roi.lon,
                    alt
                    )
        self._vehicle.send_mavlink(msg)
dataset/ETHPy150Open dronekit/dronekit-python/dronekit/__init__.py/Gimbal.target_location/swapped operands of `-`