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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 str2bool_or_none(string_, default='raise'):
 """ Convert a string to a bool or to None. Parameters string_ : str default : {'raise', False} Default behaviour if none of the "true" or "none" strings is detected. Returns ------- bool_or_none : bool or None Examples -------- True True False """

    if is_none(string_, default=False):
        return None
    else:
        return str2bool(string_, default)