{"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"let"}]}
                        let generics = generics(self.db, origin.either(|f| f.into(), |a| a.into()));
                        let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
                        let parameters = generics.bound_vars_subst(self.db, self.in_binders);