Yeah I've memorized it by now:

for i in range(len(lst) // batch_size + 1): batch = lst[i * batch_size : (i + 1) * batch_size]

Same but for the ‘batch’, ‘ibatch’, and ‘abatch’ functions I started writing back in 2008.

What do you mean by "empty sequence in"? The function doesn't raise if the input iterable is empty: it only raises if the chunk size n is 0. While that does have a natural interpretation of returning an infinite sequence of empty tuples, such a behavior would be qualitatively different than for other chunk sizes. The caller would never be able to retrieve any elements from the input iterable, and the output would be infinite even if the input is finite. In that light, it makes some sense (IMO) to avoid letting applications hit such an edge case unintentionally.