static Set<S> mechListsReferencedInJavaXSnippet(S snippetID) {
  L<S> patterns = mL("JavaX patterns referencing a mech list");
  final L<S> tok = javaTokSnippet(snippetID);
  ret asCISet(concatMap(patterns, func(S pat) -> L<S> {
    map firstQuotedToken(jextractAll(pat, tok))
  }));
}