(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code ReturnTypeMismatch)
  (message "function `main` returns wrong type")
  (file "<fixture>")
  (span
    (bytes 16 66)
    (range 4 1 5 32)
  )
  (expected "i32")
  (found "unit")
)