Note that these patterned functions take a third parameter, which is an array of "preprocessor" functions. It will be applied to the listed parameters. This is for backward compatibility. If we have a route that looks like this:

```
this.router.get("/foo/:bar/:baz", someFunc, [parseInt]);
```

This only applies `parseInt` to the `:bar` variable, but not the `:baz` variable. If you look into the test file, the last few tests should be a little clearer.