every tick in "world":
    loop all players:
        loop-player is wearing a chain chestplate named "&cJetpack"
        loop-player is sneaking
        open chest with 1 rows named "&r" to loop-player
        format slot 3 of loop-player with book named "&a&lENABLE &7Speed" with lore "&7Click to enable your speed effect" to close then run [make player execute command "/effect %player% speed 10000 12 true"]

        format slot 5 of loop-player with book named "&c&lDISABLE &7Speed" with lore "&7Click to disable your speed effect" to close then run [make player execute command "/effect %player% speed 0 0"]