Ryudo is free software, and is Copyright (c) 2019-20022 Derek Stevens,
  2004 by Russ Cox, and 1994-1996 by David Hogan.  Permission is granted
  to all sentient beings to use this software, to make copies of it,
  and to distribute those copies, provided that:

      (1) the copyright and licence notices are left intact (2) the
      recipients are aware that it is free software (3) any unapproved
      changes in functionality are either
            (i) only distributed as patches
        or (ii) distributed as a new program which is not called 9wm
                and whose documentation gives credit where it is due
      (4) the author is not held responsible for any defects
          or shortcomings in the software, or damages caused by it.

  There is no warranty for this software.  Have a nice day.