Need to apply abstract classes in Codeigniter

How to apply abstract classes in Codeigniter within an additional library of 3rd parts, i would like to know how to apply them and know what alternatives Codeigniter has to work with.
I'm also interested to know if I can apply OOP to work on the framework.
From now on thanks to the whole community and I wait for your answers.
reference source: https://www.w3schools.com/php/php_oop_cl...stract.asp

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CodeIgniter 4 is a OOP Framework.

Take a look at system/Model and the BaseModel the BaseModel is an abstract class.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )