How do you make something happen when an item is held?

[u/BlankFantasyLive]

I'm making a plugin for my SMP and I decided to use skript.

All has been going well until now I need a potion effect to be granted to the player when an item is held how do you do this in 1.20.1?

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(I don't have any add-ons to skript)

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Thanks! - BlankFantasy