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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 build_order_by(self, use_alias=True):
 """ Generates the sql for the ORDER BY portion of the query :type use_alias: bool :param use_alias: If True, the alias for the field will be used in the order by. This is an option before query windows do not use the alias. Defaults to True. :return: the ORDER BY portion of the query :rtype: str """

        # check if there are any sorters
        if len(self.sorters):
            sorters = []

            # get the sql for each sorter
            for sorter in self.sorters:
                sorters.append(sorter.get_name(use_alias=use_alias))
            return 'ORDER BY {0} '.format(', '.join(sorters))
        return ''