LJ::journal_base — Returns URL of a user's journal.
uuser. User hashref or username of user whose URL to make.
vhost. What type of URL. Acceptable options are "users", to make a http://user.site.com/ URL; "tilde" to make http://site.com/~user/; "community" for http://site.com/community/user; or the default will be http://site.com/users/user. If unspecifed and uuser is a user hashref, then the best/preferred vhost will be chosen.
The tricky thing is that users with underscores in their usernames can't have some_user.site.com as a hostname, so that's changed into some-user.site.com.
scalar; a URL.