Kivymd app , payload

def app(payload):
  from kivy.app import App
  from kivymd.theming import ThemeManager
  from kivymd.uix.screen import Screen
  from kivymd.uix.button import MDRectangleFlatButton
  from kivymd.uix.label import MDLabel
  from kivymd.uix.textfield import MDTextField
  from kivy.config import Config
  Config.set('graphics', 'resizable', '0')
  Config.set('graphics', 'width', '400')
  Config.set('graphics', 'height', '400')
  class DemoApp(App):
    def build(self):
      self.theme_cls = ThemeManager()
      self.theme_cls.primary_palette = "Red"
      screen = Screen()
      label = MDLabel(text='Payload:',
        halign='left',
        pos_hint={'center_x': .5, 'center_y': .8},
        theme_text