\newcommand\bme{\newwrite\example@out\immediate\openout \example@out hello.exa}% fopen
\newcommand\hello[2][\@empty]{%
\ifx#1\@empty%1 No option
\def\temp@val{1 : }%
\else% Option
\def\temp@val{#1 : }%
\fi%
\immediate\write\example@out{\temp@val #2}#2}% fwrite
\newcommand\eme{\immediate\closeout\example@out}% fclose