def _convert_data(self, data, data_type, num_recs, num_values, num_elems):
        '''
        Converts data to the appropriate type using the struct.unpack method,
        rather than using numpy.
        '''

        if (data_type == 51 or data_type == 52):
            return [data[i:i+num_elems].decode('utf-8') for i in
                    range(0, num_recs*num_values*num_elems, num_elems)]
        else:
            tofrom = self._convert_option()
            dt_string = self._convert_type(data_type)
            form = tofrom + str(num_recs*num_values*num_elems) + dt_string
            value_len = CDF._type_size(data_type, num_elems)
            return list(struct.unpack_from(form,
                                           data[0:num_recs*num_values*value_len]))
Converts data to the appropriate type using the struct.unpack method,
        rather than using numpy.