iters: Use `sliding_window` and `pad` for `lagged_generators_zipped`.
iters: Use `sliding_window` and `pad` for `lagged_generators_zipped`.

DudLab/nanshe,jakirkham/nanshe,DudLab/nanshe,jakirkham/nanshe,nanshe-org/nanshe,nanshe-org/nanshe