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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 sort_values(self, by, ascending=True):
 """Sort the DataFrame based on a column. Unlike Pandas, one can sort by data from both index and regular columns. Currently possible to sort only on a single column since Weld is missing multiple-column sort. Note this is an expensive operation (brings all data to Weld). Parameters by : str or list of str Column names to sort. ascending : bool, optional Returns ------- DataFrame DataFrame sorted according to the column. """

        check_type(ascending, bool)
        check_str_or_list_str(by)
        by = as_list(by)

        if len(by) > 1:
            raise NotImplementedError('Weld does not yet support sorting on multiple columns')

        all_data = self.reset_index()
        by_data = all_data[by]

        sorted_indices = weld_sort(by_data._gather_data_for_weld(),
                                   by_data._gather_weld_types(),
                                   'sort_index',
                                   ascending=ascending)

        new_index = self.index._iloc_indices(sorted_indices)
        new_columns = list(self._iter())
        new_column_names = [column.name for column in new_columns]
        new_columns = [_series_iloc(column, sorted_indices, new_index) for column in new_columns]
        new_data = OrderedDict(zip(new_column_names, new_columns))

        return DataFrame(new_data, new_index)