Function err 

pub fn err<T, E>(err: E) -> Ready<Result<T, E>> 

👎Deprecated since 3.0.2:

Use core::future::ready(Err(err)) instead.

Creates a future that is immediately ready with an error value.

Examples

use actix_utils::future::err;

let a = err::<(), _>(1);
assert_eq!(a.await, Err(1));