-- return any boxed column - specific definitions below
getBColumn :: Text -> BColMap a -> V.Vector a
getBColumn nm cms = 
    let mclm = Map.lookup nm cms
    in case mclm of
            Just v -> v
            Nothing -> V.fromList []
getBColumn :: Text -> BColMap a -> V.Vector a
getBColumn nm cms = 
    let mclm = Map.lookup nm cms
    in case mclm of
            Just v -> v
            Nothing -> V.fromList []
getBColumn nm cms = 
    let mclm = Map.lookup nm cms
    in case mclm of
            Just v -> v
            Nothing -> V.fromList []