// Explicit validation, a constrained field, and an API requirement.
(#fn below-100 ((value #u64)) #bool
  (#return (#u64::lt value 100u64)))

(#type Small (#where (value #u64) (#call below-100 ((value value)))))
(#struct Request () ((count Small) (tag #u64)))

(#fn send ((request (#ref Request))) #u64
  (#return (#get request count)))

(#fn submit ((value #u64)) #u64
  (#requires (#call below-100 ((value value))))
  (#let request Request (#struct-literal Request ((count value) (tag 0u64))))
  (#let response #u64 (#call send ((request (#borrow request)))))
  (#forget request)
  (#return response))

(#fn main () #u64
  (#let input #u64 42u64)
  (#return (#if-valid (#call below-100 ((value input)))
    (#call submit ((value input)))
    1u64)))