content: import time
  
  from dash import Dash, Input, Output, dcc, html
  
  from .utils import get_background_callback_manager
  
  background_callback_manager = get_background_callback_manager()
  handle = background_callback_manager.handle
  
  app = Dash(__name__)
  app.layout = html.Div(
      [
          dcc.Input(id="input", value="initial value"),
          html.Div(html.Div([1.5, None, "string", html.Div(id="output-1")])),
      ]
  )
  
  
  @app.callback(
      Output("output-1", "children"),
      [Input("input", "value")],
      interval=500,
      manager=background_callback_manager,
      background=True,
  )
  async def update_output(value):
      time.sleep(0.1)
      return value
  
  
  if __name__ == "__main__":
      app.run(debug=True)
  