Except as specifically provided by law, an appropriation may not be used for travel, transportation, and subsistence expenses for a meeting. This section does not prohibit—
((1)) an agency from paying the expenses of an officer or employee of the United States Government carrying out an official duty; and
((2)) the Secretary of Agriculture from paying necessary expenses for a meeting called by the Secretary for 4–H Boys and Girls Clubs as part of the cooperative extension work of the Department of Agriculture.