static Set<S> collectAngleBracketVars(S s) {
  ret collectAngleBracketVars(javaTokWithAngleBrackets(s));
}

static Set<S> collectAngleBracketVars(LS tok) {
  Set<S> set = ciSet();
  for i over tok:
    if (isAngleBracketVar(tok.get(i)))
      set.add(tok.get(i));
  ret set;
}