def _index_iterator(column_size, max_size, mix_index=False):
        """
            This will iterate over the indexes and return a list of indexes
        :param column_size: list of int of the size of each list
        :param max_size: int of the max number of iterations
        :param mix_index: bool if True will go first then last then middle
        :return: list of int of indexes
        """
        # todo implement a proper partial factorial design
        indexes = [0] * len(column_size)

        index_order = [0]
        if mix_index:
            for i in range(1, max(column_size)):
                index_order += [-1 * i, i]
        else:
            index_order += range(1, max(column_size))

        for i in range(max_size):
            yield [index_order[indexes[i]] for i in range(len(indexes))]

            for index in range(len(column_size)):
                indexes[index] += 1
                if indexes[index] < column_size[index]:
                    break

                indexes[index] = 0
                if index == len(column_size) - 1:
                    if sys.version_info[0] == 2:
                        raise StopIteration()
                    else:
                        return