parseMaybeAttr :: (ArrowXml a) => String -> a XmlTree (Maybe String)
parseMaybeAttr s = withDefault (getAttrValue0 s >>^ Just) Nothing
parseMaybeAttr :: (ArrowXml a) => String -> a XmlTree (Maybe String)
parseMaybeAttr s = withDefault (getAttrValue0 s >>^ Just) Nothing
parseMaybeAttr s = withDefault (getAttrValue0 s >>^ Just) Nothing