sbool reTok_modify_check;

static LS lambdaMapLike reTok_modify(IF1<LS> f, L<S> tok, int i, int j) {

  ret reTok_modify(tok, i, j, f);

}

static LS reTok_modify(L<S> tok, int i, int j, IF1<LS> f) {

  // extend i to an "N" token

  // and j to "C" (so j-1 is an "N" token)

  i = i & ~1;

  j = j | 1;

  L<S> t = javaTok(joinSubList(tok, i, j));

  if (f != null) {

    t = f.get(t);

    if (reTok_modify_check)

      assertEquals("Improperly tokenized", javaTok(join(t)), t);

  }

  replaceListPart(tok, i, j, t);

  ret tok;

}