问如何在另一个函数中获得访问Varibles的函数

EN

#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
import math
from geometry_msgs.msg import Quaternion
from sensor_msgs.msg import Imu
import numpy as np
from rclpy.qos import qos_profile_sensor_data

class S_E(Node):
   def __init__(self):
       super().__init__('s_e')
        self.sub = self.create_subscription(Imu, '/imu', self.callback, qos_profile=qos_profile_sensor_data)

   def callback(self, msg):

       quat        = self.quat     = msg.orientation       # x,y,z
       a_rate      = self.a_rate   = msg.angular_velocity  # x,y,z
       
       return quat, a_rate


   def estimation(self):
       print("Hello")

       quat, a_rate  = callback()
       estimate      =  (0.5 * a_rate)  * quat
       print(estimate)




def main(args=None):
   rclpy.init(args=args)  # initialize ROS2 Library
   s_e = S_E()  # make an object of class 
   try:
       while (1):
           rclpy.spin(s_e)
   except Exception as e:
       print("Exception: {}".format(e))
   

   rclpy.spin(s_e)
   
   rclpy.shutdown()


if __name__ == '__main__':
   main()