on right click on villager:
    if display name of event-entity is "&cUPGRADE":
        set {_upgrade} to chest inventory with 5 rows named "&cUPGRADE"
        set slot (integers between 0 and 45) of {_upgrade} to orange stained glass pane named "&7"
        set slot 22 of {_upgrade} to diamond pickaxe
        open {_upgrade} to player

on inventory click:
    if event-inventory is not player's inventory:
        if name of event-inventory is "&cUPGRADE":
            cancel event
            if clicked slot is 22:
                if player's tool type is pickaxe:
                    stop