```lua
function export.tr(text, lang, sc)

    if not sc then
        sc = require("Module:scripts").findBestScript(text, require(
                                                          "Module:languages").getByCode(
                                                          "az")):getCode()
    end

    if sc == "Arab" then
        text = nil
    elseif sc == "Latn" then
        text = nil
    elseif sc == "Cyrl" then
        text = mw.ustring.gsub(text, "()([ЕеЮюЁё])",
                               function(pos, iotated)
            -- modifier letter apostrophe or right single quotation mark
            local preceding = mw.ustring.sub(text, math.max(1, pos - 2),
                                             math.max(0, pos - 1))
            local capital = iotated == "Е" or iotated == "Ю"
            local lower = mw.ustring.lower(iotated)

            local translit
            if preceding == "" or mw.ustring.match(preceding,
                                                   "[АОӨӘУЫЕЯЁЮИЕаоөәуыэяёюиеъь%A][́̀]?$") then
                if capital then
                    if lower == "ю" then
                        return "Yu"
                    elseif lower == "ё" then
                        return "Yo"
                    else
                        return "Ye"
                    end
                else
                    if lower == "ю" then
                        return "yu"
                    elseif lower == "ё" then
                        return "yo"
                    else
                        return "ye"
                    end
                end
            else
                if capital then
                    if lower == "ю" then
                        return "Ü"
                    elseif lower == "ё" then
                        return "Ö"
                    else
                        return "E"
                    end
                else
                    if lower == "ю" then
                        return "ü"
                    elseif lower == "ё" then
                        return "ö"
                    else
                        return "e"
                    end
                end
            end
            return translit
        end)

        text = mw.ustring.gsub(text, '.', single_letters)
    end

    return text
end
```