fn interleave_pending(self) -> InterleavePending<Self>
    where
        Self: Sized,
    {
        InterleavePending::new(self)
    }
Introduces an extra [`Poll::Pending`](futures_core::task::Poll::Pending)
in between each call to poll.

# Examples

```
use core::pin::pin;

use futures::task::Poll;
use futures::future::{self, Future};
use futures_test::task::noop_context;
use futures_test::future::FutureTestExt;

let future = future::ready(1).interleave_pending();
let mut future = pin!(future);

let mut cx = noop_context();

assert_eq!(future.as_mut().poll(&mut cx), Poll::Pending);
assert_eq!(future.as_mut().poll(&mut cx), Poll::Ready(1));
```
futures-test/src/future/mod.rs