% language switches.
\newif\ifen
\newif\ifru

\newcommand{\en}[1]{\ifen#1\fi}
\newcommand{\ru}[1]{\ifru#1\fi}

% language detection.
\def\liten{en}                         % english literal.
\def\litru{ru}                         % russian literal.
\def\litnil{}                          % empty literal.
\getenv[\lang]{RESUME_LANG}            % read shell variable.
\ifdefequal{\lang}{\liten}{\entrue}{}  % use english.
\ifdefequal{\lang}{\litru}{\rutrue}{}  % use russian.
\ifdefequal{\lang}{\litnil}{\entrue}{} % use english by default.

% include translations.
\input{i18n/month}
