Function event_loop_receiver_option 

pub fn event_loop_receiver_option<T: 'static, E: 'static>(
    receiver: impl PollableReceiver<Item = T, Error = E> + 'static,
    write: WriteSignal<Option<T>>,
    write_error: WriteSignal<Option<E>>,
    trigger: ExtSendTrigger,
)

Execute a pollable receiver on the main event loop, for Option signals. The receiver does not need to be Send.