{"ast_node_type":"other","tokens":[{"end":83,"kind":"keyword","start":0,"text":"(self.fallback)(var,"}]}
                (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
                let default = self.table.fallback_value(var, kind).cast(Interner);
                    .assert_ty_ref(Interner)