appendHeader rq k (Just v) = rq
    { _rqHeaders = DList.snoc (_rqHeaders rq) (k, Text.encodeUtf8 v)
    }
appendHeader rq k (Just v) = rq
    { _rqHeaders = DList.snoc (_rqHeaders rq) (k, Text.encodeUtf8 v)
    }
appendHeader rq k (Just v) = rq
    { _rqHeaders = DList.snoc (_rqHeaders rq) (k, Text.encodeUtf8 v)
    }