type Either[A, B] = object
  a:   A
  b:   B
  isA: bool

proc test(input: string): Either[string, int] =
  if blahblahblah:
    return Either[string, int](a: input, isA: true)
  return Either[string, int](b: 123)

let out = test("Test")
if out.isAl:
  let str = out.a
else:
  let num = out.b