getDataURI :: MediaBag -> Maybe String -> MimeType -> String
       -> IO String
getDataURI _ _ _ src@('d':'a':'t':'a':':':_) = return src
getDataURI :: MediaBag -> Maybe String -> MimeType -> String
       -> IO String
getDataURI _ _ _ src@('d':'a':'t':'a':':':_) = return src
getDataURI _ _ _ src@('d':'a':'t':'a':':':_) = return src