Is it correct to say function?

I am new to CI and PHP. I am studying
https://codeigniter.com/user_guide/libra...onfig.html

There are two ways to load a config file:
Manual Loading
To load one of your custom config files you will use the following function within the controller that needs it:


We know when we call by object it is called a method, however the above line used the term function , Why?