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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 new_status(self, new_status):
 """ Sets the new_status of this BuildSetStatusChangedEvent. :param new_status: The new_status of this BuildSetStatusChangedEvent. :type: str """

        allowed_values = ["NEW", "DONE", "REJECTED"]
        if new_status not in allowed_values:
            raise ValueError(
                "Invalid value for `new_status` ({0}), must be one of {1}"
                .format(new_status, allowed_values)
            )

        self._new_status = new_status