sS andCombineRegexps(LS regexps) {
  if (l(regexps) == 1) ret first(regexps);
  if (empty(regexps)) ret "";
  StringBuilder out = new("^");
  for i over regexps:
    if (i < l(regexps)-1)
      out.append("(?=.*?" + regexps.get(i) + ")");
    else
      out.append(".*?" + regexps.get(i));
  ret str(out);
}

sS andCombineRegexps(S... regexps) {
  ret andCombineRegexps(asList(regexps));
}