A language negotiation service.
There are no attributes or fields specified.
getLanguage(langs, env)
Return the matching language to use.
The decision of which language to use is based on the list of available languages, and the given user environment. An IUserPreferredLanguages adapter for the environment is obtained and the list of acceptable languages is retrieved from the environment.
If no match is found between the list of available languages and the list of acceptable languages, None is returned.
Arguments: