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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 fixed_legend_filter_sort(self, fixed_legend_filter_sort):
 """Sets the fixed_legend_filter_sort of this ChartSettings. Whether to display \"Top\"- or \"Bottom\"-ranked series in the fixed legend # noqa: E501 :param fixed_legend_filter_sort: The fixed_legend_filter_sort of this ChartSettings. # noqa: E501 :type: str """

        allowed_values = ["TOP", "BOTTOM"]  # noqa: E501
        if fixed_legend_filter_sort not in allowed_values:
            raise ValueError(
                "Invalid value for `fixed_legend_filter_sort` ({0}), must be one of {1}"  # noqa: E501
                .format(fixed_legend_filter_sort, allowed_values)
            )

        self._fixed_legend_filter_sort = fixed_legend_filter_sort