static S replaceVars(S s, Map<S, S> map) {
  ret join(replaceVars(javaTok(s), map));
}
  
static L<S> replaceVars(L<S> tok, Map<S, S> map) {
  tok = cloneList(tok);
  for (S var : keys(map)) {
    S value = map.get(var);
    jreplace(tok, var, value);
  }
  ret tok;
}