Using Implicit Returns in Functions

00:00 Now let’s look at Python’s return statement. The Python return statement is a statement used inside a function or method to send the function’s result back to where the function was called.

00:12 It consists of the keyword return followed by an optional return value. The return value can be any Python object, but remember—everything in Python is an object.

00:27 So you can return numbers, collection types—basically anything. If you don’t provide a return value, Python will return the value None. If you don’t even have a return statement, Python will still return None.

00:47 These last two cases are examples of an implicit return value, and we’ll look at that first. Again, if you don’t provide a return value, or if you don’t even have a return statement, None will be used as the return value.

01:04 Keep in mind if you’re calling functions interactively, where normally you see the return value of a function—if the return value is None, the interpreter won’t display it.

01:14 Python’s print() function is an example of a function that returns None, because we think of it as not actually returning a value at all.

01:24 If we just print something,

01:29 we see the output, but no return value. If we actually want to see the return value, let’s save the result of the function call to a variable.

01:46 We still see the output, but now we can see the value of return_value by printing it.

01:56 As you can see, it is None. Here’s another example. If a return statement isn’t provided, then it too is going to have a return value of None.

02:09 So if I define my function add_one(), it takes a parameter, which we’ll call x, and notice we don’t have a return statement at all.

02:20 We’re going to create a variable result to save what we get when we add 1 to x. But that’s it. If I call add_one() and provide it a number, we’re expecting 6 because within the function, 6 was computed, but we didn’t do anything with it. Again, if I want to see the return value, let’s save it.

02:55 This function didn’t return a value. It didn’t have a return statement at all, and so Python used None as its return value. Perhaps the author of this function meant to return the result, and we’ll take a look at how that’s done next when we look at explicit return statements.