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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 _parse_user_flags():
 """ Parses user-flags file and loads it to register user defined options. """

    try:
        idx = list(sys.argv).index('--user-flags')
        user_flags_file = sys.argv[idx + 1]
    except (ValueError, IndexError):
        user_flags_file = ''

    if user_flags_file and os.path.isfile(user_flags_file):
        from ryu.utils import _import_module_file
        _import_module_file(user_flags_file)