"step" parameter to load frames has no effect

[eldar]

I am looking at the data loading function and in particular at its step parameter:

https://github.com/simonmeister/UnFlow/blob/master/src/e2eflow/core/input.py#L164-L165

It appears though, that regardless of the choice of the step, only consecutive frames are used, because frames are indexed by i and i+1. I would assume the indexing to be i and i+step. Is this a bug or I misunderstand the intention behind this parameter?