Function scoped_result 

pub fn scoped_result<T, E, F>(fut: F) -> impl Future<Output = Result<T, E>>
where
    F: Future<Output = Result<T, E>>,
    E: From<String>,

scoped, but the RESULT is refused if the account changed while it ran.

For an operation whose value goes back to the UI. The work itself completed correctly against its own account; what must not happen is that value being painted into, or acted on by, the account now on screen. One wrapper in place of a check before every write.