Trying to access information from another function

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Here is my code

def callback(data):

    #rospy.loginfo(data.position[1])

    print(data.position[0])

    x = data.position[0]

    return x



def listener():

    rospy.init_node('listener')

    rospy.Subscriber('/rrbot/joint_states', JointState, callback) 
    rospy.spin()


def talker():

    pub = rospy.Publisher('/rrbot/joint1_position_controller/command', Float64, queue_size=10)
    rospy.init_node('talker', anonymous=True)

    rate = rospy.Rate(1) # 10hz
    while not rospy.is_shutdown():
        #hello_str = "hello world %s" % rospy.get_time()
        force = random.choice([-1,1])
        #force = 0
        rospy.loginfo(force)
        pub.publish(force)
        rate.sleep()
        return force

def trainer():

    force = talker()

    x = callback(data)

    print(force)
    print(x)


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

this is my error when i try to run the code

NameError: name 'data' is not defined