pub fn lazy<F, R>(f: F) -> Lazy<F>
where
    F: FnOnce(&mut Context<'_>) -> R,
{
    assert_future::<R, _>(Lazy { f: Some(f) })
}
Creates a new future that allows delayed execution of a closure.

The provided closure is only run once the future is polled.

# Examples

```
# futures::executor::block_on(async {
use futures::future;

let a = future::lazy(|_| 1);
assert_eq!(a.await, 1);

let b = future::lazy(|_| -> i32 {
panic!("oh no!")
});
drop(b); // closure is never run
# });
```
futures-util/src/future/lazy.rs