message: These can use range syntax
diff: @@ -12,7 +12,6 @@ use std::cmp::max;
  use std::collections::BTreeMap;
  use std::convert::TryFrom;
  use std::mem;
  -use std::ops::Bound::{Included, Unbounded};
  use std::rc::Rc;
  use smallvec::SmallVec;
  @@ -69,10 +68,8 @@ impl RxStreamOrderer {
  return;
  }
  - let extend = if let Some((&prev_start, prev_vec)) = self
  - .data_ranges
  - .range_mut((Unbounded, Included(new_start)))
  - .next_back()
  + let extend = if let Some((&prev_start, prev_vec)) =
  + self.data_ranges.range_mut(..=new_start).next_back()
  {
  let prev_end = prev_start + u64::try_from(prev_vec.len()).unwrap();
  if new_end > prev_end {
  @@ -150,7 +147,7 @@ impl RxStreamOrderer {
  if extend {
  let (_, buf) = self
  .data_ranges
  - .range_mut((Unbounded, Included(new_start)))
  + .range_mut(..=new_start)
  .next_back()
  .unwrap();
  buf.extend_from_slice(to_add);
  