message: Get rid of an option in setup_eval
  Summary: Test code, so perf is irrelevant, so get rid of Option which really meant a no-op setup_eval and just use a no-op intead.
diff: @@ -203,7 +203,7 @@ pub struct Assert<'a> {
  modules: HashMap<String, FrozenModule>,
  globals: Globals,
  gc_strategy: Option<GcStrategy>,
  - setup_eval: Option<Box<dyn Fn(&mut Evaluator)>>,
  + setup_eval: Box<dyn Fn(&mut Evaluator)>,
  // Ideally `print_handler` should be set up in `setup_eval`
  // but if you know how to do it, show me how.
  print_handler: Option<&'a (dyn PrintHandler + 'a)>,
  @@ -222,7 +222,7 @@ impl<'a> Assert<'a> {
  modules: hashmap!["assert.star".to_owned() => Lazy::force(&ASSERT_STAR).dupe()],
  globals: Lazy::force(&GLOBALS).dupe(),
  gc_strategy: None,
  - setup_eval: None,
  + setup_eval: box |_| (),
  print_handler: None,
  }
  }
  @@ -233,7 +233,7 @@ impl<'a> Assert<'a> {
  }
  pub fn setup_eval(&mut self, setup: impl Fn(&mut Evaluator) + 'static) {
  - self.setup_eval = Some(box setup);
  + self.setup_eval = box setup;
  }
  pub fn set_print_handler(&mut self, handler: &'a (dyn PrintHandler + 'a)) {
  @@ -267,9 +267,7 @@ impl<'a> Assert<'a> {
  let loader = ReturnFileLoader { modules: &modules };
  let ast = AstModule::parse(path, program.to_owned(), &self.dialect)?;
  let mut eval = Evaluator::new(module);
  - if let Some(setup_eval) = &self.setup_eval {
  - setup_eval(&mut eval);
  - }
  + (self.setup_eval)(&mut eval);
  if let Some(print_handler) = self.print_handler {
  eval.set_print_handler(print_handler);
  }
  