GNU GENERAL PUBLIC LICENSE
Version 2, June 1991

Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License,
version 2 or any later version, as published by the Free
Software Foundation.

https://www.gnu.org/licenses/gpl-2.0.html