public static <A> S join(S glue, Iterable<A> strings) {
  if (strings == null) ret "";
  if (strings cast Collection) {
    if (strings.size() == 1) ret str(first(strings));
  }
  new StringBuilder buf;
  Iterator<A> i = strings.iterator();
  if (i.hasNext()) {
    buf.append(i.next());
    while (i.hasNext())
      buf.append(glue).append(i.next());
  }
  ret buf.toString();
}

public static S join(S glue, S... strings) {
  ret join(glue, Arrays.asList(strings));
}

static <A> S join(Iterable<A> strings) {
  ret join("", strings);
}

static <A> S join(Iterable<A> strings, S glue) {
  ret join(glue, strings);
}

public static S join(String[] strings) {
  ret join("", strings);
}

ifclass Pair
static S join(S glue, Pair p) {
  ret p == null ? "" : str(p.a) + glue + str(p.b);
}
endif

Began life as a copy of #2000507