-- | The union of a list of maps.
--
-- > unions [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])]
-- >     == fromList [(3, "b"), (5, "a"), (7, "C")]
-- > unions [(fromList [(5, "A3"), (3, "B3")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "a"), (3, "b")])]
-- >     == fromList [(3, "B3"), (5, "A3"), (7, "C")]
unions :: [IntMap a] -> IntMap a
unions = Data.Foldable.foldl' union empty
unions :: [IntMap a] -> IntMap a
unions = Data.Foldable.foldl' union empty
unions = Data.Foldable.foldl' union empty