code: def cache_fn():
      return app._cache_key.value
  
imports: from dash import Dash, Input, State, Output, dcc, html
  import time
  from multiprocessing import Value
  from tests.integration.long_callback.utils import get_long_callback_manager
label_desc: Use image node_id 1 for calling a global function with example usage: cache_fn() and returns: app