You've seen Boolean's functions end of statements. We're going to investigate a style issue now that can happen when you combine all three. We're going to start by writing a function that returns true if the parameter is even, and false otherwise. As an example, if a call is even with value four and hoping that I get back true. And if a call is even 77, then hopefully I'll get back false. We can tell that we're sending it back an int and that we hope to get back a Bool. Our header is we're going to call the function as even and let's call the parameter num because that's a number. And, What we're going to do here is return other numb is even. Now, that I know the, the details of my function, it's time to figure out some code that will let me know whether a number is even or odd. I'm going to investigate this in the Python shell. And, notice that if I divide four by two, there is no remainder. But, if I divide three or five or seven by two, there is a remainder. So, we're going to try out mod for mod two is zero, 77 mod two is one. And so, any number I pick that is odd is going to have a remainder of one, when I divide it by two. Continuing this thought, four mod two = zero is true. But, something like 77 mod two = zero is false. So, this expression, the number mod two equals zero is going to give me the result that I want. We might decide to write something like, if num mod two is zero, then return true otherwise return false. This will certainly work. Let's explore that. I will run this so we can have it there. Now, I can access the is even int function and say, hey, there's even four? Yes, it is. How about three? No, that's false. So our function works. However, The function body here is three lines too long. I don't actually need to use an if statement. The issue here is that, num mod two equals zero is already a Boolean expression. As we saw over here, four mod two = zero produced the value true. I don't need to say if something is true, then return true, Otherwise, if it wasn't true, return false. I can actually come into this out and replace it with a single line. I want to return a Boolean. Num mod two equals zero produces a Boolean, so I can just do return num mod two equals zero. Let's try this new version out in the shell. I still get true, I still get false. So, my new version works just as well as the old one. Its shorter, and after a while, you are going to find it preferable to the longer version of the if and the else. Working with Boolean expressions is new to many of you, and so this may make you a little uncomfortable, it might seem a little fancy or even confusing. Play with it for awhile, see what you can come up with in the shell when you need a Boolean expression, and see if you can simplify some of your return statements. If you ever find yourself doing if something where to return true, otherwise, return false.
