static <A> Collection<A> printStructLines(Collection<A> l) {
  ret pnlStruct(l);
}

static <A> Iterable<A> printStructLines(Iterable<A> l) {
  ret pnlStruct(l);
}

static <A> A[] pnlStruct(A[] l) {
  ret pnlStruct(l);
}

static <A, B> Map<A, B> pnlStruct(Map<A, B> map) {
  ret pnlStruct(map);
}