static L<S> isYes_yesses = litlist("y", "yes", "yeah", "y", "yup", "yo", "corect", "sure", "ok", "afirmative"); // << collapsed words, so "corect" means "correct"

static boolean isYes(S s) {
  ret isYes_yesses.contains(collapseWord(toLowerCase(firstWord2(s))));
}