syntax_data: {"ast_node_type":"other","tokens":[{"end":16,"kind":"keyword","start":0,"text":")"}]}
source_snippet:     ) -> I::Ty {
context_before:         coroutine_captures_by_ref_ty: I::Ty,
context_after:         let tupled_upvars_ty = Self::tupled_upvars_by_closure_kind(