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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 _add_none_handler(validation_callable, # type: Callable none_policy # type: int ):
 """ Adds a wrapper or nothing around the provided validation_callable, depending on the selected policy :param validation_callable: :param none_policy: an int representing the None policy, see NonePolicy :return: """

    if none_policy is NonePolicy.SKIP:
        return _none_accepter(validation_callable)  # accept all None values

    elif none_policy is NonePolicy.FAIL:
        return _none_rejecter(validation_callable)  # reject all None values

    elif none_policy is NonePolicy.VALIDATE:
        return validation_callable                  # do not handle None specifically, do not wrap

    else:
        raise ValueError('Invalid none_policy : ' + str(none_policy))