how can I change the mod key in awesome wm from windows key to meta?

I recently got a happy hacking keyboard 2 professional that has a meta key instead of windows keys. Since I used to use the windows key to change between screens in awesome window manager (local modkey = "Mod4") how can I change that to use meta instead?

right now I have in my rc.lua

local modkey = "Mod4"

local altkey = "Mod1"

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