{"ast_node_type":"function","tokens":[{"end":85,"kind":"keyword","start":0,"text":"fn"}]}
    fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy<'hir> {
        hir::MutTy { ty: self.lower_ty(&mt.ty, itctx), mutbl: mt.mutbl }