Imagine a screen where a user inputs a meal that they've eaten. If the user taps a "save" button without adding any food, you might want to prompt the user that they haven't actually added anything. Using the Food struct and the text fields provided below, create a function called logFood that takes no parameters and returns an optional Food object. Inside the body of the function, use a guard statement to unwrap the text property of food TextField and calories TextField. In addition to unwrapping calories TextField, you'll need to create and unwrap a new variable that initializes an Int from the text in caloriesTextField. If any of this fails, return nil. After the guard statement, create and return a Food object.