=head2 for_session
-Returns a serialized user for storage in the session. Currently, this is the value of the field
-specified by the 'id_field' config variable.
+Returns a serialized user for storage in the session.
=head2 from_session
-Revives a serialized user from storage in the session. Currently, this uses the serialized data as the
-value of the 'id_field' config variable.
+Revives a serialized user from storage in the session.
=head2 get ( $fieldname )