local function sedol(s)
    if not(type(s) == "string" and #s == 6) then return false end
    local weights = {1, 3, 1, 7, 3, 9}
    local sum = 0
    for i = 1, 6 do
        local c = s[i]
        if not c:isupper() and not(c in "0123456789") then
            return nil
        end
        if c in "AEIOU" then return nil end
        sum += tonumber(c, 36) * weights[i]
    end
    local cd = (10 - sum % 10) % 10
    return s .. $"{cd}"
end

local tests = {
    "710889",
    "B0YBKJ",
    "406566",
    "B0YBLH",
    "228276",
    "B0YBKL",
    "557910",
    "B0YBKR",
    "585284",
    "B0YBKT",
    "B00030",
    "I23456"
}

for tests as test do
    local ans = sedol(test) ?? "not valid"
    print($"{test} -> {ans}")
end