Bind the *domain* to the locale directory *localedir*. More concretely,
:mod:`gettext` will look for binary :file:`.mo` files for the given domain using
the path (on Unix): :file:`{localedir}/{language}/LC_MESSAGES/{domain}.mo`, where
- *languages* is searched for in the environment variables :envvar:`LANGUAGE`,
+ *language* is searched for in the environment variables :envvar:`LANGUAGE`,
:envvar:`LC_ALL`, :envvar:`LC_MESSAGES`, and :envvar:`LANG` respectively.
If *localedir* is omitted or ``None``, then the current binding for *domain* is