{"ast_node_type":"function","tokens":[{"end":58,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn ty_is_opaque_future(self, ty: Ty<'_>) -> bool {
    /// Given a `ty`, return whether it's an `impl Future<...>`.
        let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = ty.kind() else { return false };