void main() {
  Map<String, int> scoreboard = {};

  var playerOne = "Victor";
  var scoreOne = 1337;
  newScore(scoreboard, playerOne, scoreOne);

  var scoreTwo = 420;
  newScore(scoreboard, playerOne, scoreTwo);

  var scoreThree = 1400;
  newScore(scoreboard, playerOne, scoreThree);

  print(scoreboard);
}

void newScore(Map<String, int> scoreboard, String name, int score) {
  var savedScore = scoreboard[name];

  if (savedScore == null) {
    scoreboard[name] = score;
    return;
  }

  if (savedScore < score) {
    scoreboard[name] = score;
    return;
  }
}