{"ast_node_type":"function","tokens":[{"end":80,"kind":"keyword","start":0,"text":"fn"}]}
    fn visit_rvalue(&mut self, rvalue: &mir::Rvalue<'tcx>, location: Location) {
impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
        debug!("visiting rvalue {:?}", *rvalue);