// DEFINE YOUR FUNCTION BELOW:
    function returnDay(num){
        const days = [null,'Monday',"Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"];
        
      if(num >0 && num <8){
            return days[num]
        }else return null
    }

//using ternary operator
    function returnDay(num){
        const days = [null,'Monday',"Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"];
        return num> 0 && num < 8 ?days[num] : null;
    }