// adds default constructor to classes with "persistable" modifier
svoid tok_persistableClasses(LS tok) {
  int i;
  
  while((i = jfind(tok, "persistable", tokCondition {
    while (int j = i+1; isIdentifier(_get(tok, j)); j += 2)
      if (eqGet(tok, j, "class"))
        true;
    false;
  })) >= 0) {
    int iClass = indexOf(tok, "class", i);
    int idx = indexOf(tok, iClass, "{");
    L<S> contents = subList(tok, idx+1, j);
    LS contentsWithoutCurly = replaceCurlyBracedWith(tok_combineCurlyBrackets_keep(cloneList(contents)), "");
    bool hasDefaultConstructor = jcontains(contentsWithoutCurly, "*()");
    if (!hasDefaultConstructor)
      tokAppend_reTok(idx, "\n  *() {}");
    clearTokens_reTok(i, i+2); // drop persistable keyword
  }
}