docs: def save_stack(stack):
      """
      Saves a stack object to a flatfile.
  
      :param caliendo.hooks.CallStack stack: The stack to save.
  
      """
      global CACHE_
      serialized = pickle.dumps(stack, PPROT)
      CACHE_['stacks']["{0}.{1}".format(stack.module, stack.caller)] = serialized
      write_out()