How do I Pass on functions (as arguments) between scripts?

I'm trying to make two scripts communicate.

One passes a function as an argument to another when .new() is called.

What is the best way to implement this?

For example, I have tried passing a function as an argument to fill a Bindable function event

function GUI.new(PARENT, CLICKEFFECT, CARD)
    local card = Instance.new("ImageButton", PARENT)
    local clickEffect = Instance.new("BindableFunction", card)
    clickEffect.OnInvoke = (CLICKEFFECT)
    card.MouseButton1Down:connect(clickEffect:Invoke); --ERROR how do I get around this?
end

--And in a seperate ModuleScript
Card = GUI.new(SomeRandomObject, function()print(i)end , SomeRandomCard)