// DEFINE YOUR FUNCTION BELOW:
function returnDay(numOfDay) {
  const days = {
    1: 'Monday',
    2: 'Tuesday',
    3: 'Wednesday',
    4: 'Thursday',
    5: 'Friday',
    6: 'Saturday',
    7: 'Sunday'
  }

  const keys = Object.keys(days);
  const values = Object.values(days);

  for (let i = 0; i < keys.length; i++) {
    if (numOfDay === parseInt(keys[i])) {
      return values[i];
    }
  }
  return null;
}