How do libraries work in 5.7? I am trying to utilize a custom library for use on a single page.

I have created the single page view and controller. I am able to access the controller from the view.

I also created a library in application/libraries/ called testlib.php.

In my controller I have Loader::library('testlib'); Inside of the library there is only one function right now called sayHello()

In my controller I make a call to the function using: sayHello();. However, I receive the following error Call to undefined function sayHello(). What am I missing to make this work in 5.7?