+ hasHeader ∷ CIAscii → a → Bool
+ {-# INLINE hasHeader #-}
+ hasHeader key a
+ = case getHeaders a of
+ Headers m → key M.∈ m
+
+ getCIHeader ∷ CIAscii → a → Maybe CIAscii
+ {-# INLINE getCIHeader #-}
+ getCIHeader key a
+ = A.toCIAscii <$> getHeader key a
+