isExpiredStamp
  :: UTCTime
  -> IO Bool
isExpiredStamp stamp = do
  current <- getCurrentTime
  let diff = diffUTCTime current stamp
  return $ diff < 0 || diff > 300
isExpiredStamp
  :: UTCTime
  -> IO Bool
isExpiredStamp stamp = do
  current <- getCurrentTime
  let diff = diffUTCTime current stamp
  return $ diff < 0 || diff > 300
isExpiredStamp stamp = do
  current <- getCurrentTime
  let diff = diffUTCTime current stamp
  return $ diff < 0 || diff > 300