How to move the robot to a goal

i already fix the problem with the original code that you have to move to a goal, the problem was the need of some dependencies. Now I am doing a code to search in different goals base on the probability that the object, which the robot is looking for is near to that point/goal, the code is the next:

#!/usr/bin/env python3

import rospy
import actionlib
import sys
import pickle
from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
from geometry_msgs.msg import Quaternion,Pose
from tf import transformations
import math
import time
import transforms3d.quaternions as quaternions
import transforms3d.quaternions as euler


class Points:
    def __init__(self,id,x,y,weight,C1,C2,C3,C4,C5):
        self.id = id
        self.x = x 
        self.y = y
        self.weight = weight
        self.C1 = C1
        self.C2 = C2
        self.C3 = C3
        self.C4 = C4
        self.C5 = C5
"""class list:
    def points_order(self,i):
        root='src/stretch_ros/maps/points/reference_points_3.pickle'
        #root='reference_points_3.pickle'
        with open(root, 'rb') as file:
            list = pickle.load(file)
            high_weight=sorted(list, key=lambda list: list.weight,reverse=True)
            print(high_weight)
            print("ID:",high_weight[0].id)
            print("X:",high_weight[0].weight)
            print("puntos:",len(high_weight))
            return [high_weight[i].x,high_weight[i].y]"""
    
class StretchNavigation:
    """
    A simple encapsulation of the navigation stack for a Stretch robot.
    """
    def __init__(self):
        """
        Create an instance of the simple navigation interface.
        :param self: The self reference.
        """
        self.client = actionlib.SimpleActionClient('move_base', MoveBaseAction)
        self.client.wait_for_server()
        rospy.loginfo('{0}: Made contact with move_base server'.format(self.__class__.__name__))

        self.goal = MoveBaseGoal()
        self.goal.target_pose.header.frame_id = 'map'
        self.goal.target_pose.header.stamp = rospy.Time()

        self.goal.target_pose.pose.position.x = 0.0
        self.goal.target_pose.pose.position.y = 0.0
        self.goal.target_pose.pose.position.z = 0.0
        self.goal.target_pose.pose.orientation.x = 0.0
        self.goal.target_pose.pose.orientation.y = 0.0
        self.goal.target_pose.pose.orientation.z = 0.0
        self.goal.target_pose.pose.orientation.w = 1.0
        self.position=None
        self.orientation=None
    

    def get_quaternion(self,theta):
        """
        A function to build Quaternians from Euler angles. Since the Stretch only
        rotates around z, we can zero out the other angles.
        :param theta: The angle (radians) the robot makes with the x-axis.
        """
        return Quaternion(*transformations.quaternion_from_euler(0.0, 0.0, theta))
    def get_euler_angle(self,x,y,z,w):
        rot_matrix = quaternions.quat2mat([w,x,y,z])
        return euler.mat2quat(rot_matrix)
    def distance(self,x1,x2,y1,y2):
        return math.sqrt((x1-x2)**2+(y1-y2)**2)

    def go_to(self):
        """
        Drive the robot to a particular pose on the map. The Stretch only needs
        (x, y) coordinates and a heading.
        :param x: x coordinate in the map frame.
        :param y: y coordinate in the map frame.
        :param theta: heading (angle with the x-axis in the map frame)
        """
   
        rospy.Subscriber('robot_pose', Pose, nav.position_callback)
        rospy.Subscriber('robot_pose', Pose, nav.orientation_callback)
        root='src/stretch_ros/maps/points/reference_points_3.pickle'
            #root='reference_points_3.pickle'
        with open(root, 'rb') as file:
                list = pickle.load(file)
                high_weight=sorted(list, key=lambda list: list.weight,reverse=True)
                """print(high_weight)
                print("ID:",high_weight[0].id)
                print("X:",high_weight[0].weight)
                print("puntos:",len(high_weight))"""
                
        """nav.listener(nav.position_callback)
        position=nav.listener(nav.position_callback)
        nav.listener(nav.orientation_callback)
        orientation=nav.listener(nav.orientation_callback)"""""
        


        for s in range(len(high_weight)):
            # Update theta
            region_probability = 0
            theta = 0
            for i in range (5):
                if high_weight[s].C1 < region_probability:
                    region_probability=high_weight[s].C1
                    theta = math.pi/2
                if high_weight[s].C2 < region_probability:
                    region_probability=high_weight[s].C2
                    theta = math.pi/2+(2/5)*math.pi
                if high_weight[s].C3 < region_probability:
                    region_probability=high_weight[s].C3
                    theta = math.pi/2+(4/5)*math.pi
                if high_weight[s].C4 < region_probability:
                    region_probability=high_weight[s].C4
                    theta = math.pi/2+(6/5)*math.pi
                if high_weight[s].C5 < region_probability:
                    region_probability=high_weight[s].C5
                    theta = math.pi/2+(8/5)*math.pi

            # Go to point
            #rospy.loginfo('{0}: Heading for ({1}, {2}) at {3} radians'.format(self.__class__.__name__,x, y, theta))

            self.goal.target_pose.pose.position.x = high_weight[s].x
            self.goal.target_pose.pose.position.y = high_weight[s].y
            self.goal.target_pose.pose.orientation = self.get_quaternion(theta)
            print(self.goal)

            self.client.send_goal(self.goal, done_cb=self.done_callback)
            self.client.wait_for_result()

            # While until reached
            point_reached = False
            while not point_reached:
                distance_treshoald= 0.01
                theta_treshoald=(1/36)*math.pi
                orientation=self.orientation
                position=self.position
                #distance=math.sqrt((high_weight[s].x-position[0])**2+(high_weight[s].y-position[1])**2)
                diference_of_angle=theta-self.get_euler_angle(orientation[3],orientation[0],orientation[1],orientation[2])
                # Check if reached
                if distance_treshoald<self.distance(high_weight[s].x,position[0],high_weight[s].y,position[1]) and diference_of_angle<theta_treshoald:
                    print("Point reached: ","ID: ",high_weight[s].id,"Weight: ",high_weight[s].weight)
                    point_reached = True
                # Sleep
                time.sleep(1)

    def done_callback(self, status, result):
        """
        The done_callback function will be called when the joint action is complete.
        :param self: The self reference.
        :param status: status attribute from MoveBaseActionResult message.
        :param result: result attribute from MoveBaseActionResult message.
        """
        if status == actionlib.GoalStatus.SUCCEEDED:
            rospy.loginfo('{0}: SUCCEEDED in reaching the goal.'.format(self.__class__.__name__))
        else:
            rospy.loginfo('{0}: FAILED in reaching the goal.'.format(self.__class__.__name__))
    def position_callback(self,pose):
        self.position=pose.position
        
    def orientation_callback(self,pose):
        self.orientation=pose.orientation
    
    def listener(self,callback):
        rospy.init_node('listener',anonymous=True)
        rospy.Subscriber('robot_pose', Pose, callback)
    """def callback(pose):
        position=pose.position
        orientation=pose.orientation"""
    

if __name__ == '__main__':
    rospy.init_node('navigation', argv=sys.argv)
    nav = StretchNavigation()
    nav.go_to()

But i have problem because it says that some of the variables that I use to check that the robot is close enough to send other goal are not subscribable.