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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _file_notifier(state):
 """Notify of configuration update through file. Arguments: state (_WaffleState):
 Object that contains reference to app and its configstore. """

    tstamp = time.time()
    state._tstamp = tstamp
    conf = state.app.config

    file_path = conf.get('WAFFLE_WATCHER_FILE', '/tmp/waffleconf.txt')

    if not os.path.isfile(file_path):
        # Create watch file
        open(file_path, 'a').close()

    # Update timestamp
    os.utime(file_path, (tstamp, tstamp))