Copyright (c) 1998-2002 by Peter Norvig.

Permission is granted to anyone to use this software, in source or
object code form, on any computer system, and to modify, compile,
decompile, run, and redistribute it to anyone else, subject to the
following restrictions:

- The author makes no warranty of any kind, either expressed or
implied, about the suitability of this software for any purpose.

- The author accepts no liability of any kind for damages or other
consequences of the use of this software, even if they arise from
defects in the software.

- The origin of this software must not be misrepresented, either by
explicit claim or by omission.

- Altered versions must be plainly marked as such, and must not be
misrepresented as being the original software. Altered versions may be
distributed in packages under other licenses (such as the GNU
license).

If you find this software useful, it would be nice if you let me,
(peter@norvig.com) know about it, and nicer still if you send me
modifications that you are willing to share. However, you are not
required to do so.