 value
       → Route ()
header n v = modify (\(r, hs) → (r, Header n v : filter (\(Header k _) → k ≠ n) hs))
{-# INLINE header #-}

-- | Set Content-Type header
--
-- > serve 80 [contentType "
header ∷ B.ByteString -- ^ Header name
       → B.ByteString -- ^ Header value
       → Route ()
header n v = modify (\(r, hs) → (r, Header n v : filter (\(Header k _) → k ≠ n) hs))
header n v = modify (\(r, hs) → (r, Header n v : filter (\(Header k _) → k ≠ n) hs))