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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 weight_unit(self, weight_unit):
 """Sets the weight_unit of this MeasurementSettings. :param weight_unit: The weight_unit of this MeasurementSettings. :type: str """

        allowed_values = ["pound", "kilogram"]  # noqa: E501
        if weight_unit is not None and weight_unit not in allowed_values:
            raise ValueError(
                "Invalid value for `weight_unit` ({0}), must be one of {1}"  # noqa: E501
                .format(weight_unit, allowed_values)
            )

        self._weight_unit = weight_unit