How can I overwrite interface function?

I don’t understand how I can overwrite an interface function. I can implement an interface function (from an interface blueprint) with an event. But how do you overwrite the function like in the UE4 documentation. Does the documentation mean that you should implement the interface function with an event in a Parent class and then overwrite the function in the child class?:

ttps://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/Types/Interface/UsingInterfaces/

I don’t understand the UE4 documentation on this issue. Implementing a Blueprint interface with an event? Implementing a blueprint Interface in a Child class with overwriting the function?

Another Blueprint must implement your interface.
Suppose that you want to call Get Health on your Character Blueprint anywhere.
Then your Character Blueprint must implement an interface that has a Get Health function.
Assuming that you’ve successfully created an interface blueprint earlier, open the Character Blueprint.
Click on the Blueprint Props button in the toolbar
In the Details->Interface tab add the interface that implements the Get Health function.
Now back in the My Blueprint tab you’ll see that Get Health has appeared under Interfaces.
Double click this function.
Assuming that your character has a Health variable you can connect this variable to the ReturnNode.

Now whenever you need to access the health of your character, you can add a Get Health node in any Blueprint with target input Get Player Pawn

It depends on return value, void tends to create custom event (in reliable manner with specified category) rather than interface function to override