text: import dash
  from dash.dependencies import Input, Output
  import dash_html_components as html
  from datetime import datetime
  import time
  
  app = dash.Dash()
  
  app.layout = html.Div(
      [
          html.Button("execute callbacks", id="button_2"),
          html.Div(children="callback not executed", id="first_output_2"),
          html.Div(children="callback not executed", id="second_output_2"),
          html.Div(children="callback not executed", id="third_output_2"),
          html.Div(children="callback not executed", id="fourth_output_2"),
      ]
  )
  
  
  @app.callback(
      Output("first_output_2", "children"),
      Output("second_output_2", "children"),
      Input("button_2", "n_clicks"), prevent_initial_call=True)
  def first_callback(n):
      now = datetime.now()
      current_time = now.strftime("%H:%M:%S")
      return ["in the first callback it is " + current_time, "in the first callback it is " + current_time]
  
  
  @app.callback(
      Output("third_output_2", "children"), Input("second_output_2", "children"), prevent_initial_call=True)
  def second_callback(n):
      time.sleep(2)
      now = datetime.now()
      current_time = now.strftime("%H:%M:%S")
      return "in the second callback it is " + current_time
  
  
  @app.callback(
      Output("fourth_output_2", "children"),
      Input("first_output_2", "children"),
      Input("third_output_2", "children"), prevent_initial_call=True)
  def third_output(n, m):
      time.sleep(2)
      now = datetime.now()
      current_time = now.strftime("%H:%M:%S")
      return "in the third callback it is " + current_time
  
  
  if __name__ == '__main__':
      app.run_server(debug=True)
  