{"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"coroutine_source:"}]}
        coroutine_source: hir::CoroutineSource,
        coroutine_kind: CoroutineKind,
    ) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>) {