 
 <prompt> How person fit make things slow down? <response>: The second way wey dem take solve the problem na based on the idea of class, and e define set as class wey dey belong to other classes, while proper class na class wey no dey belong to other classes. Under the Zermelo-Fraenkel approach, the axioms dey stop the construction of set wey get all sets wey no dey belong to themselves. But under von Neumann approach, the class wey get all sets wey no dey belong to themselves fit be constructed, but e go be proper class and no be set. 