if let Some(req) = {
if ! downbound.is_empty() {
outstanding.pop_front()
} else if let Some((i,_)) = outstanding.iter().enumerate().find({
|(_,o)| outstanding.len() > o.oi.target_requests_outstanding.sat()
if let Some(req) = {
if ! downbound.is_empty() {
outstanding.pop_front()
} else if let Some((i,_)) = outstanding.iter().enumerate().find({
|(_,o)| outstanding.len() > o.oi.target_requests_outstanding.sat()