Function after_ready 

pub async fn after_ready<T, E, RF, Op, OF>(
    ready: RF,
    operation: Op,
) -> Result<T, E>
where
    RF: Future<Output = Result<(), E>>,
    Op: FnOnce() -> OF,
    OF: Future<Output = Result<T, E>>,

Run operation only after ready resolves Ok, returning the readiness error unchanged if it does not.

Generic over the result and error so the short-circuit law is unit-testable without pyo3; the RDMA bindings instantiate E = PyErr and this helper never inspects or remaps it. operation is a closure, not an already-started future, so no effect begins before readiness. The typical ready input is PyHandle::wait_completion.