test_cast = do
  Ok serv <- start $ return $ Counter 1
  call serv Get >>= assertEqual 1
  cast serv Inc
  call serv Get >>= assertEqual 2
test_cast = do
  Ok serv <- start $ return $ Counter 1
  call serv Get >>= assertEqual 1
  cast serv Inc
  call serv Get >>= assertEqual 2
test_cast = do
  Ok serv <- start $ return $ Counter 1
  call serv Get >>= assertEqual 1
  cast serv Inc
  call serv Get >>= assertEqual 2