How to create bash script to do/undo setting locale with one alias? -

how create bash script (to make alias of it), doing this:

if lang=en_us.utf-8 "unset lang" else "export lang=en_us.utf-8" 

adding

en() { if [[ $lang == "en_us.utf-8" ]] unset lang else export lang=en_us.utf-8 fi } 

to ~/.bash_profile works!