AttributeError: 'KeyboardEvent' object has no attribute 'click_loop'

Я создал легкую программу с помощью библиотеки kivy. Я пытаюсь вызвать цикл, через функцию, при нажатии клавишы, но у меня вылетает ошибка:

 AttributeError: 'KeyboardEvent' object has no attribute 'click_loop'

Вот мой код:

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.image import Image
from kivy.uix.slider import Slider
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.textinput import TextInput
import pyautogui
import keyboard
import time
from kivy.clock import Clock
loop=None
class MainApp(App):
    def build(self):
        layout = FloatLayout(size=(1000, 1000))
        button=Button(text='Start',on_press=self.start_tr,pos_hint={'center_x': .4, 'center_y': .4},size_hint=(.13, .13))
        button2 = Button(text='Stop', on_press=self.stop_tr,pos_hint={'center_x': .6, 'center_y': .4},size_hint=(.13, .13))
        layout.add_widget(button)
        layout.add_widget(button2)
        return layout

    def click_loop(self,*args):
        print(1)
        #pyautogui.click(pyautogui.position())
    def start_tr(self,*args):
        Clock.schedule_interval(self.click_loop, 1)
    def stop_tr(self,*args):
        Clock.unschedule(self.click_loop)
    keyboard.on_press_key('y', start_tr)
    keyboard.on_press_key('x', stop_tr)
if __name__ == '__main__':
    MainApp().run()