How would I use this?

I am not good with metatables, but I get the basic idea of them.

But I am not too sure, by following the wiki, it does not say how to use this: http://wiki.roblox.com/index.php?title=Sandboxing

If anyone can tell me how to use the code below, I set a bounty of 30 robux.

local needssandboxing = function(i) end

sandbox = {}
sandbox.cache = {}


local function safeDestroy(obj)
    if obj:IsA("Script") then
        print("You cannot destroy a Script")
    elseif obj:IsA("Part") then
        print("You cannot destroy a part")
    end 

    obj:Destroy()
end

local function safeGetChildren(obj)
    local res = {}

    for k,v in pairs(obj:GetChildren()) do
    if not v.Name:match("^Hide") then
            table.insert(res,v)
        end
    end

    return res
end

sandbox.mt = {
    __index = function(self, k)
        local original = sandbox.cache[self]
        local v = original[k]

        if k:lower() == "destroy" then
            return sandbox.any(safeDestroy)

        elseif k:lower() == "getchildren" or k:lower() == "children" then
            return sandbox.any(safeGetChildren)
        end

        return sandbox.any(v)
    end,

    __newindex = function(self, k, v)
        local original = sandbox.cache[self]
        original[k] = unsandbox.any(v)
    end
}

function sandbox.any(a)
    if sandbox.cache[a] then
        return a

    elseif type(a) == "function" then
        return sandbox.func(a)

    elseif type(a) == "table" then
        return sandbox.table(a)

    else
        return value
    end
end

function sandbox.object(o)
    local sandboxed = setmetatable({}, sandbox.mt)

    sandbox.cache[sandboxed] = o

    return sandboxed
end

function sandbox.func(f)
    local sandboxed = function(...)
        return sandbox(f(unsandbox(...)))
    end

    sandbox.cache[sandboxed] = f

    return sandboxed

end

function sandbox.table(t)
    local sandboxed = {}

    for k, v in pairs(t) do
        sandboxed[sandbox.any(k)] = sandbox.any(v)
    end

    return sandboxed
end

unsandbox = {}

unsandbox.any = function(a)
    if sandbox.cache[a] then
        return sandbox.cache[a]

    elseif type(a) == "function" then
        return unsandbox.func(a)

    elseif type(a) == "table" then
        return unsandbox.table(a)

    else
        return a
    end
end

unsandbox.table = function(t)
    local unsandboxed = {}

    for k, v in pairs(t) do
        unsandboxed[unsandbox.any(k)] = unsandbox.any(v)
    end

    return unsandboxed
end

unsandbox.func = function(f)
    local raw = function(...)
        return unsandbox(f(sandbox(...)))
    end

    sandbox.cache[f] = raw 

    return raw
end

local callable_mt = {
   __call = function(self, first, ...)
       if select('#', ...) == 0 then
           return self.any(first)
       else
           return self.any(first), self(...)
       end
   end
}

setmetatable(sandbox, callable_mt)
setmetatable(unsandbox, callable_mt)