LoG: Alcove Gem Puzzle

function check()
    local counter = 0

    for alcoveitem in findEntity("redalcove"):containedItems() do
        if alcoveitem.name == "red_gem" then
            counter = counter + 1
            break
        end
    end

    for alcoveitem in findEntity("greenalcove"):containedItems() do
        if alcoveitem.name == "green_gem" then
            counter = counter + 1
            break
        end
    end

    for alcoveitem in findEntity("bluealcove"):containedItems() do
        if alcoveitem.name == "blue_gem" then
            counter = counter + 1
            break
        end
    end

    if counter == 3 then
        findEntity("exitdoor1"):open()
        findEntity("exitdoor2"):open()
    end
end