Need help with functions?

Ok so Here is a working script

local NintendoToSega = game.Players.LocalPlayer.PlayerGui.ChooseCharacter.NintendoToSega

function onClick4()
if NintendoToSega.Visible
then NintendoToSega.Visible = false
end
end

button.MouseButton1Click:connect(onClick4)

I need to know A way to write it If it is not visible it will be visible because I have tried

local SegaToNintendo = game.Players.LocalPlayer.PlayerGui.ChooseCharacter.SegaToNintendo

function onClick5()
if SegaToNintendo.Visible = false
then SegaToNintendo.Visible
end
end

button.MouseButton1Click(onClick5)

And Then there is a red line under = for "= false" Please Help