I was implementing and comparing some metrics. In the calculation of the HHI [here](https://github.com/guillermo-navas-palencia/optbinning/blob/0720b8dd2b60a723cfb16e1f830da1d62598171a/optbinning/binning/piecewise/binning_statistics.py#L139) shouldn't this be masked - `hhi(p_records[mask])` - to avoid including empty bins in the calculation ? Best, Lucas