[Solved] Error when subscribing to multiple topics in python

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Hello, I'm new to ROS and I'm having a problem when I try to move my turtle to a goal that I'm publishing. I created a node that subscribes to 2 topics: the position of the turtle and the goal_position. The goal_position topic is being published in the terminal. The node also publishes the velocity of the turtle. The purpose of this node is that when the turtle arrives at the goal position, it will then go to the following goal. I tried to this code in python without using class in the following code, however I received the error:

NameError: global name 'goal_pose' is not defined
NameError: global name 'pose' is not defined

What I don't understand is that I've defined them both.

#!/usr/bin/env python

import rospy
from geometry_msgs.msg import Twist
from turtlesim.msg import Pose
from math import po`enter code here`w, atan2, sqrt
import angles, math

goal = False

def update_pose(data):
    global pose 
    pose = data
    pose.x = round(pose.x, 4)
    pose.y = round(pose.y, 4)

def update_goal(data1):
    global goal_pose
    goal_pose = data1
    goal_pose.x = round(goal_pose.x, 4)
    goal_pose.y = round(goal_pose.y, 4)

def turtleWalk():
    global pose,pub,vel_msg,goal_pose,goal
    linear_gain = 4
    angular_gain = 12
    distance_tolerance = 0.1
    vel_msg = Twist()

    while not goal:
        distance  = round(sqrt(pow((goal_pose.x - pose.x), 2) + pow((goal_pose.y - pose.y), 2)), 3)
        linear_vel = linear_gain*distance   
        steering_angle = round(atan2(goal_pose.y - pose.y, goal_pose.x - pose.x),4) 
        angular_vel = angular_gain*(angles.shortest_angular_distance(pose.theta,steering_angle))
        while distance >= distance_tolerance:

            vel_msg.linear.x = linear_vel
            vel_msg.angular.z = angular_vel

            pub.publish(vel_msg)
        goal = True 

def turtleController(): 
    global pub,vel_msg,goal_pose,pose

    rospy.init_node('turtle_controller',anonymous=True)
    pub = rospy.Publisher('/turtle1/cmd_vel',Twist,queue_size=10)
    rospy.Subscriber('/turtle1/pose',Pose,update_pose)
    rospy.Subscriber('/goal',Pose,update_goal)
    rate = rospy.Rate(10)

    while not rospy.is_shutdown():
        turtleWalk()
        rate.sleep()
    vel_msg.linear.x = 0        
    vel_msg.angular.z = 0
    pub.publish(vel_msg)

if __name__ == '__main__':
    try:
        turtleController()
    except rospy.ROSInterruptException:
        pass

The error happens in line 31 which is :

  distance  = round(sqrt(pow((goal_pose.x - pose.x), 2) + pow((goal_pose.y - pose.y), 2)), 3)