{"ast_node_type":"function","tokens":[{"end":58,"kind":"keyword","start":0,"text":"fn"}]}
    fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx>;
    fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx>;
    fn replace_const(&mut self, bc: ty::BoundConst) -> ty::Const<'tcx>;