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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 rule_str2rule(rule_str, prob):
 # type: (str, float) -> Rule """ A helper function that converts the resulting string returned from C function to the Rule object :param rule_str: a string representing the rule :param prob: the output probability :return: a Rule object """

    if rule_str == "default":
        return Rule([], prob)

    raw_rules = rule_str[1:-1].split(",")
    clauses = []
    for raw_rule in raw_rules:
        idx = raw_rule.find("=")
        if idx == -1:
            raise ValueError("No \"=\" find in the rule!")
        clauses.append(Clause(int(raw_rule[1:idx]), int(raw_rule[(idx + 1):])))
    return Rule(clauses, prob)