{-# INLINE pushE #-}

sliceB :: MapBuffer a -> Int -> Int -> [a]
sliceB (MB pos vec) start num = -- V.toList $ V.slice (pos+start) num vec
  let ix1 = pos+start
      top = snd $ M.split (ix1-1) vec
  in  map snd . M.toAscList . fst $ M.split (ix1+num) top
{-# INLINE sliceB #-}