(typename $errno
    (enum u32
        $ok
        $invalid_arg
        $dont_want_to
        $physically_unable
        $picket_line))

(typename $excuse
  (enum u8
     $dog_ate
     $traffic
     $sleeping))

(module $foo
  (@interface func (export "bar")
    (param $an_int u32)
    (param $an_float f32)
    (result $error $errno))
  (@interface func (export "baz")
    (param $an_excuse $excuse)
    (result $error $errno))
)