-- | Nominal attribute constructor.
a_nominal :: (Show a) => [a] -> String -> Attribute
a_nominal xs a = Attribute (NominalAttribute (putNominal a) xs) a
a_nominal :: (Show a) => [a] -> String -> Attribute
a_nominal xs a = Attribute (NominalAttribute (putNominal a) xs) a
a_nominal xs a = Attribute (NominalAttribute (putNominal a) xs) a