{"ast_node_type":"variable","tokens":[{"end":84,"kind":"keyword","start":0,"text":"let"}]}
                        let ref_ty = self.new_ref_ty(pat.span, pat_mutbl, inner_ty);
                        let inner_ty = self.next_ty_var(inner.span);
                        debug!("check_pat_ref: demanding {:?} = {:?}", expected, ref_ty);