syntax_data: {"ast_node_type":"other","tokens":[{"end":35,"kind":"keyword","start":0,"text":"coroutine_def_id:"}]}
source_snippet:         coroutine_def_id: I::DefId,
context_before:         coroutine_kind_ty: I::Ty,
context_after:         tupled_upvars_ty: I::Ty,