message: AssignModifyOp typedef
  Summary: Code readability, helpful in the following diffs.
diff: @@ -200,6 +200,9 @@ fn eval_assign_list<'v>(
  }
  }
  +pub(crate) type AssignModifyOp =
  + for<'v> fn(Value<'v>, Value<'v>, &mut Evaluator<'v, '_>) -> anyhow::Result<Value<'v>>;
  +
  impl Compiler<'_> {
  pub fn assign(&mut self, expr: CstAssign) -> AssignCompiled {
  let span = expr.span;
  @@ -253,7 +256,7 @@ impl Compiler<'_> {
  span_stmt: Span,
  lhs: CstAssign,
  rhs: ExprCompiledValue,
  - op: for<'v> fn(Value<'v>, Value<'v>, &mut Evaluator<'v, '_>) -> anyhow::Result<Value<'v>>,
  + op: AssignModifyOp,
  ) -> StmtsCompiled {
  let span_lhs = lhs.span;
  match lhs.node {
  