Add a key function in editor

Hello
I have been making my horror game for the past few months now and I just recently downloaded a blueprint for a light switch. In the editor under default settings, I noticed an option to select what key you want to use to be able to click on it.
I want to add this feature to other objects but I cannot figure out how can someone please help me.
Thank you

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Create a new variable in your blueprint, set the variable type to “key”, compile, and set a default value

then click the eyeball icon

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Ok, but how would you incorporate that into your blueprint to make it do a function?

from the blueprint panel, you can drag it onto your blueprint and click “get key”

or you can right-click on the blueprint and type “get key”

then do whatever you want with it

I get the whole set and get key but what is an example of an implementation of it in a blueprint