Create a function that takes in a current mood and return a sentence in the following format: "Today, I am feeling {mood}". However, if no argument is passed, return "Today, I am feeling neutral".
mood_today("happy") ➞ "Today, I am feeling happy"
mood_today("sad") ➞ "Today, I am feeling sad"
mood_today() ➞ "Today, I am feeling neutral"