static <A> A getOr(L<A> l, int i, A defaultValue) {
  ret or(get(l, i), defaultValue);
}

ifclass DoubleBuffer
static double getOr(DoubleBuffer l, int i, double defaultValue) {
  if (i >= 0 && i < l(l)) ret l.get(i);
  ret defaultValue;
}
endif

Began life as a copy of #1029271