But this is necessary. Isn't it? If I have e.g. the kernels `[1, 1, 1, 1, 1]` and  `[1, 1, 1]`, the slice would be just `slice(1:4)`. And if dont't copy the whole array the result would be `[2, 2, 2]` instead of `[1, 2, 2, 2, 1]`. Or am I missing something?