function randomHand() {
  const hand = [];
  for (let i = 0; i < GAME_STATE.num_cards_per_hand; i++) {
    hand.push(getRandomDigit());
  }
  return hand.sort((a, b) => a - b);
}
Yields a randomly generated array of three elements.  Each element
is an integer randomly selected within the range [1, 9].  Hands are returned
in sorted order.