def _add_defaults(def_callback, in_row, in_col_ndx_map, out_col_ndx_map,
    out_row, callback=None):
    """
    Assigns defaults to the generated output rows.

    :return: the generated output rows
    :rtype: list
    """
    if callback:
        out_rows = callback(in_row, in_col_ndx_map, out_col_ndx_map, out_row)
    else:
        out_rows = [out_row]
    for row in out_rows:
        def_callback(row, out_col_ndx_map)
    return out_rows
