patmatnew.scala:526: warning: match is not exhaustive!

    def go(tok : Token) = tok.matching match {
                              ^
patmatnew.scala:595: warning: match is not exhaustive!

      (None:Option[Boolean]) match {
           ^
patmatnew.scala:815: warning: match is not exhaustive!

      (EmptyTree: Tree) match {
                ^
warning: there were unchecked warnings; re-run with -unchecked for details
four warnings found