Functions can optionally return a value. To specify the return type, it is added to the function signature, similar to how variables and parameters do. Here's a simple example of a function that returns an integer:
## Return types
```
fn add_one(x: int): int {}
```
Note that this function won't compile, since it doesn't actually return anything. Let's fix that by adding a `return` statement with an expression:
```
fn add_one(x: int): int {
return x + 1
}
```
Now, if you call the function with `1` as its argument and read its value, you will see the computed result: