title: How to get the value of slider which defined inside screen widget in kivy
body: <p>I am making one kivy file and linking with python file. I defined slider inside screen in kivy and thought access inside the python. But getting error like this <code>AttributeError: 'super' object has no attribute '__getattr__'</code>after running the below main.py file</p>
  
  <p>Here is main.py</p>
  
  <pre><code>from kivy.app import App
  from kivy.lang import Builder
  from kivy.uix.screenmanager import ScreenManager, Screen, SlideTransition
  
  class Maintenance(Screen):
      pass
  class ScreenManagement(ScreenManager):
     pass
  
  presentation = Builder.load_file("ex4.kv")
  
  class ex4(App):
      def __init__(self, **kwargs):
          super(ex4, self).__init__(**kwargs)
  
      def build(self):
         return presentation
      def my_value(self):
  
          print(self.root.ids.slider1.value)
  
  
  
  if __name__ == '__main__':
     ex4().run()
  </code></pre>
  
  <p>ex4.kv</p>
  
  <pre><code>#:import SlideTransition kivy.uix.screenmanager.SlideTransition
  
  ScreenManagement:
      transition:SlideTransition()
  
      Maintenance:
  &lt;Maintenance&gt;:
      name: 'screen1'
      BoxLayout:
          orientation: 'vertical'
  
          Slider:
             id: slider1
             on_value:app.my_value()
  </code></pre>