title: st () takes 1 positional argument but 2 were given
body: <p>not binding function with button
  when I click button window closes</p>
  
  <p>ERROR</p>
  
  <pre><code>st () takes 1 positional argument but 2 were given
  </code></pre>
  
  <hr>
  
  <pre><code>from kivy.uix.button import  Button
  from kivy.app import App
  from kivy.uix.boxlayout import BoxLayout
  class new(BoxLayout):
      def st(self):
          print("vllghh")
      def __init__(self,**kwargs):
          super().__init__(**kwargs)
  
          self.bt=Button(text="njfhjgfg")
          self.add_widget(self.bt)
          self.bt.bind(on_press=self.st)
  class am(App):
      def build(self):
          return new()
  am().run()
  </code></pre>