-- | /O(min(n,W))/. Is the key a member of the map?
member :: Key -> IntMap a -> Bool
member k (IntMap m) = W.member (i2w k) m
member :: Key -> IntMap a -> Bool
member k (IntMap m) = W.member (i2w k) m
member k (IntMap m) = W.member (i2w k) m