From TestWiki

    Documentation for this module may be created at Module:Language/name/data/doc

    -- put tables and their tables together
    local function __coalesce(...)
        local coalesced = {}
        for _, langslist in ipairs{...} do
            for langcode, langnames in pairs(langslist) do
                for _, langname in pairs(langnames) do
                    if not coalesced[langcode] then
                        coalesced[langcode] = {}
                    table.insert(coalesced[langcode], langname)
        return coalesced
    -- make the keys lowercase
    local function __preprocess(t, first_of_array_in_array)
        local preprocessed = {}
        if first_of_array_in_array then
        	-- keep only the 1st language name for each code, excluding synonyms
            for k, v in pairs(t) do
                preprocessed[k:lower()] = {v[1]}
            for k, v in pairs(t) do
                preprocessed[k:lower()] = v
        return preprocessed
    -- all valid primary language subtags for BCP47 from IANA (most of them from ISO 639-1, -2 and -3 with some exclusions)
    local __iana_languages = __preprocess(require("Module:Language/data/iana languages"));
    -- ISO 639-3 contains additional 3-letter codes not inserted in the IANA database as they are aliased to 2-letter codes,
    -- but excludes some deleted codes still valid in BCP47 (some of them are aliased)
    local __iso_639_3      = __preprocess(require("Module:Language/data/ISO 639-3"));
    -- Wikimedia wikis uses some non-standard codes and a subset of IANA codes, plus composite codes
    local __wp_languages   = __preprocess(require("Module:Language/data/wp languages"), true);
    -- all valid script subtags for BCP47 from IANA (excluding special ISO 15924 codes)
    local iana_scripts     = __preprocess(require("Module:Language/data/iana scripts"));
    -- all valid region subtags for BCP47 from IANA (derived from ISO 3166-1 excluding special codes, and from 3-digit UN M.49 codes for groups of countries)
    local iana_regions     = __preprocess(require("Module:Language/data/iana regions"));
    -- variant subtags from IANA; table format differs from the other IANA data tables
    local iana_variants = __preprocess(require("Module:Language/data/iana variants"));
    -- suppressed script subtags from IANA;
    local iana_suppressed_scripts = __preprocess (require("Module:Language/data/iana suppressed scripts"));
    return {
        lang   = __coalesce(__wp_languages, __iana_languages, __iso_639_3),
        lang_iana = __iana_languages,
        script = iana_scripts,
        region = iana_regions,
        variant = iana_variants,
        suppressed = iana_suppressed_scripts,