addServer :: HeaderValue -> IndexedHeader -> H.ResponseHeaders -> H.ResponseHeaders
addServer defaultServerValue' rspidxhdr hdrs = case rspidxhdr ! idxServer of
    Nothing -> (hServer, defaultServerValue') : hdrs
    _       -> hdrs

----------------------------------------------------------------

-- |
--
-- >>> replaceHeader "Content-Type" "new" [("content-type","old")]
-- [("Content-Type","new")]
addServer :: HeaderValue -> IndexedHeader -> H.ResponseHeaders -> H.ResponseHeaders
addServer defaultServerValue' rspidxhdr hdrs = case rspidxhdr ! idxServer of
    Nothing -> (hServer, defaultServerValue') : hdrs
    _       -> hdrs

----------------------------------------------------------------

-- |
--
-- >>> replaceHeader "Content-Type" "new" [("content-type","old")]
-- [("Content-Type","new")]
addServer defaultServerValue' rspidxhdr hdrs = case rspidxhdr ! idxServer of
    Nothing -> (hServer, defaultServerValue') : hdrs
    _       -> hdrs

----------------------------------------------------------------

-- |
--
-- >>> replaceHeader "Content-Type" "new" [("content-type","old")]
-- [("Content-Type","new")]