static ItIt<SS> arbitraryVarsFlexMatchIC_tok_iterator(Set<S> vars, Tok pat, Tok input) {
  new LS usedVars;
  LS starsPat = arbitraryVarsToStars(pat.tok(), vars, usedVars);
  ret mapI(flexMatchIC_tok_iterator(starsPat, input.tok()),
    m -> matchesToMapUsingVarList_ciMap(m, usedVars));
}