modify version key transform (VMap tree) =
  VMap $ T.modifyVersioned (L.set cellVersion version) compareKey tree
  key ((Cell version key <$>) . transform . (getCellValue <$>))
modify version key transform (VMap tree) =
  VMap $ T.modifyVersioned (L.set cellVersion version) compareKey tree
  key ((Cell version key <$>) . transform . (getCellValue <$>))
modify version key transform (VMap tree) =
  VMap $ T.modifyVersioned (L.set cellVersion version) compareKey tree
  key ((Cell version key <$>) . transform . (getCellValue <$>))