control gimbal rate

def cmd_gimbal_rate(self, args):
        '''control gimbal rate'''
        if len(args) != 3:
            print("usage: gimbal rate ROLL PITCH YAW")
            return
        (roll, pitch, yaw) = (float(args[0]), float(args[1]), float(args[2]))
        self.master.mav.gimbal_control_send(self.target_system,
                                            mavutil.mavlink.MAV_COMP_ID_GIMBAL,
                                            radians(roll),
                                            radians(pitch),
                                            radians(yaw))