Mini-exercises

1. Using your myFavoriteSong variable from earlier, use optional binding to check if it contains a value. If it does, print out the value. If it doesn’t, print "I don’t have a favorite song."
2. Change myFavoriteSong to the opposite of what it is now. If it’s nil, set it to a string; if it’s a string, set it to nil. Observe how your printed result changes.