function setBracketItem_(rng, players) {
  if (players) {
    let rand = Math.ceil(Math.random() * players.length);
    rng.setValue(players.splice(rand - 1, 1)[0][0]);
  }
  rng.setBackgroundColor('yellow');
}
Sets the value of an item in the bracket and the color.
@param {Range} rng The Spreadsheet Range.
@param {string[]} players The list of players.