pub(all) enum ExamResult {
  Pass
  Fail
} derive(Show)

pub(all) struct Student {
  id : String
  score : Double
}

fn[A : Eq + Show] assert_eq(value : A, other : A) -> Unit

fn count_qualified_students(students : Array[Student], is_qualified : (Student) -> ExamResult) -> Int

fn is_qualified(student : Student, criteria : Double) -> ExamResult