{"ast_node_type":"function","tokens":[{"end":75,"kind":"keyword","start":0,"text":"fn"}]}
    fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx> {
impl<'a, 'tcx> BoundVarReplacerDelegate<'tcx> for FnMutDelegate<'a, 'tcx> {
        (self.regions)(br)