Question about `position_bins`

Hi,

I'm trying to understand the implementation differences between this repo and lightgbm. Does 
```
position_bins = 12       : this denotes the maximum positions taken into account.
```
effectively serve the same as `lambdarank_truncation_level` in the newer releases of lightgbm? Looks like they each cap the number of results from a given query we look at. Wanted to confirm.