+isError = doesMeet (>= 400)
+
+-- |@'isClientError' sc@ is True iff @400 <= sc < 500@.
+isClientError :: StatusCode -> Bool
+isClientError = doesMeet (\ n -> n >= 400 && n < 500)
+
+-- |@'isServerError' sc@ is True iff @500 <= sc@.
+isServerError :: StatusCode -> Bool
+isServerError = doesMeet (>= 500)
+
+
+doesMeet :: (Int -> Bool) -> StatusCode -> Bool
+doesMeet p sc = let (num, _) = statusCode sc
+ in
+ p num