This is the multilanguage.sty package for LaTeX

The solution is based upon TEX StackExchange answer by Riccardo. Apparently, this user prefers to keep an air of mystery.

** Usage: **

% MULTILINGUAL SUPPORT

%enables babel to every lang supported by your document

\usepackage[italian,english,lithuanian]{babel}

\usepackage{multilanguage}

% set short and long language codes. The second one must be known by babel

%\setdoclang{it}{italian}

%\setdoclang{en}{english}

\setdoclang{lt}{lithuanian}

% END MULTILINGUAL SUPPORT

...

% Sections, subsections, subsubsections: in the first parameter you can freely use both short or long language codes

\sectionlang{it}{Sezione 1}

\sectionlang{english}{Section 1}

% Strings that are displayed only in a certain language

\lang{it}{Questa stringa appare solo in italiano.}

\lang{en}{This string shows up only in English.}

\lang{lt}{Ši eilutė bus tik lietuviškame tekste.}

% When you have only two languages, you can simply rely on this if-else construct

\langif{it}{If vero: questo e' italiano.}{Else: this is for any language different from Italian.}