[Sharlikran]

Warning: Spoiler

function Harvest.IsValidBottle(name)
    for k, v in pairs(Harvest.bottle) do
        if v == name then
            return true
        end
    end

    return false
end

function Harvest.IsValidContainer(name)
    for k, v in pairs(Harvest.container) do
        if v == name then
            return true
        end
    end

    return false
end

function Harvest.IsValidBook(name)
    for k, v in pairs(Harvest.books) do
        if v == name then
            return true
        end
    end

    return false
end

function Harvest.IsValidEnchant(name)
    for k, v in pairs(Harvest.enchanting) do
        if v == name then
            return true
        end
    end

    return false
end

I figured it out. I was approaching it all wrong. There was already an argument to pass to the function, so all I had to do was take advantage of the name in the set. Thanks for all the advice guys.

EDIT: Updated the above post to show the sets I used.