static NulData AfUserSet int  af_group_id,
int  af_user_id,
bool  value_to_set

Allows to set/unset the relation between the given user and group.

af_group_id Group where the user will be removed/added according to value value_to_set.
af_user_id User to be added/removed from the given group according to value value_to_set.
value_to_set Value used to decide if the given user must be removed or added to the given group.