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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 start_scanner(path):
 """ watch for file events in the supplied path """

    try:
        observer = Observer()
        observer.start()
        stream = Stream(file_modified, path, file_events=True)
        observer.schedule(stream)
        print "Watching for changes. Press Ctrl-C to stop."
        while 1:
          pass
    except (KeyboardInterrupt, OSError, IOError):
        observer.unschedule(stream)
        observer.stop()