local stacks = {
    { item=ItemStack("'default:mese' 99"), added=false; },
    { item=ItemStack("'default:mese' 99"), added=false; },
    { item=ItemStack("'default:mese' 99"), added=false; },
};
local stack_count = #stacks;

local inv = player:get_inventory();

for i = 1, stack_count do
    if (not inv:room_for_item("main", stacks[i].item)) then
        for j = 1, stack_count do
            if (stacks[j].added) then
                inv:remove_item("main", stacks[j].item);
            end
        end
        break;
    end
    inv:add_item("main", stacks[i].item);
    stacks[i].added = true;
end