Without arguments return name, account, and person of the current user in a stdClass. If in or not_in are given return true if conditions are met, otherwise false.
The returned stdClass holds these members:
* *name*: a %string% holding the user name
* *account*: a %tobject% holding the account
* * person*: a %tobject% representing the user in the domain
If noone is logged in, all three are %null%.
%in% or %not_in% accept a topic reference to a user group or class or an array of thereof.