function rand(min, max){
  min = (min == null ? Number.MIN_SAFE_INTEGER : min);
  max = (max == null ? Number.MAX_SAFE_INTEGER : max);
  return min + ((max - min) * Math.random());
}

function rand(
  min = Number.MIN_SAFE_INTEGER, 
  max = Number.MAX_SAFE_INTEGER
){
  return min + ((max - min) * Math.random());
}