/// Returns the "choice regions" for a given member
/// constraint. This is the `R1..Rn` from a constraint like:
///
- /// ```
+ /// ```text
/// R0 member of [R1..Rn]
/// ```
crate fn choice_regions(&self, pci: NllMemberConstraintIndex) -> &[ty::RegionVid] {
///
/// Before:
///
-/// ```
+/// ```text
/// target_list: A -> B -> C -> (None)
/// source_list: D -> E -> F -> (None)
/// ```
///
/// After:
///
-/// ```
+/// ```text
/// target_list: A -> B -> C -> D -> E -> F -> (None)
/// ```
fn append_list(