syntax_data: {"ast_node_type":"variable","tokens":[{"end":64,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let (hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, .. }
context_before: ) -> LocalDefId {
context_after:     | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, .. }) =