code: def test_click_simple(dash_duo):
      call_count = Value("i", 0)
  
      app = Dash(__name__)
      app.layout = html.Div(
          [
              html.Div(id="container"),
              html.Button("Click", id="button", n_clicks=0),
              html.Iframe(
                  id="video",
                  allow="fullscreen",
                  referrerPolicy="origin",
              ),
          ]
      )
  
      @app.callback(
          Output("container", "children"),
          Input("button", "n_clicks"),
          # The new percy runner loads the page, so to get consistent behavior for
          # call_count we need to skip the initial call
          prevent_initial_call=True,
      )
      def update_output(n_clicks):
          call_count.value += 1
          return "clicked {} times".format(n_clicks)
  
      dash_duo.start_server(app)
  
      dash_duo.wait_for_text_to_equal("#container", "")
  
      assert call_count.value == 0
  
      dash_duo.find_element("#button").click()
  
      dash_duo.wait_for_text_to_equal("#container", "clicked 1 times")
      assert call_count.value == 1
      dash_duo.percy_snapshot("html button click")
  
      assert not dash_duo.get_logs()
  
      assert (
          dash_duo.find_element("#video").get_attribute("allow")
          == "fullscreen"
      )
      assert (
          dash_duo.find_element("#video").get_attribute(
              "referrerpolicy"
          )
          == "origin"
      )
  
imports: from multiprocessing import Value
  import time
  from dash import Dash, Input, Output, html
label_desc: Use image node_id 1 for calling a global function with example usage: test_click_simple(dash_duo) and returns: str