Function subscribe_account_diffs_many 

pub async fn subscribe_account_diffs_many<F, Fut, I, S>(
    rpc_endpoint: &str,
    accounts: I,
    on_notification: F,
) -> Result<AccountDiffSubscriptionHandle, SubscriptionError>
where
    F: Fn(RoutedAccountDiffNotification) -> Fut + Send + Sync + 'static,
    Fut: Future<Output = ()> + Send + 'static,
    I: IntoIterator<Item = S>,
    S: Into<String>,

Subscribe to account diff notifications for many accounts over a single websocket.

All requested subscriptions must be acknowledged before this returns. Once the stream is live, any websocket disconnect is treated as a fatal completeness error instead of silently reconnecting and risking dropped notifications.