text: from textual.app import App
  
  
  class Colorizer(App):
      async def on_load(self):
          await self.bind("r", "color('red')")
          await self.bind("g", "color('green')")
          await self.bind("b", "color('blue')")
  
      async def action_color(self, color: str) -> None:
          self.background = f"on {color}"
  
  
  Colorizer.run()
  