static L<S> simpleSpaces3(L<S> tok) {
  tok = cloneList(tok);
  for (int i = 0; i < l(tok); i += 2)
    if (nempty(tok.get(i))) tok.set(i, " ");
  ret tok;
}

sS simpleSpaces3(S s) {
  ret empty(s) ? s : join(simpleSpaces3(javaTok(s));
}