symbol :: Char -> BS.ByteString -> Maybe BS.ByteString
symbol c t
  | Just (c', t') <- BS.uncons t, c' == c = Just $ dropSpaces t'
  | otherwise = Nothing
symbol :: Char -> BS.ByteString -> Maybe BS.ByteString
symbol c t
  | Just (c', t') <- BS.uncons t, c' == c = Just $ dropSpaces t'
  | otherwise = Nothing
symbol c t
  | Just (c', t') <- BS.uncons t, c' == c = Just $ dropSpaces t'
  | otherwise = Nothing