pressureDrop calculation in predictive_weight.h

[geofrue]

Hello!
I am trying to adopt the release/stm32-blackpill SW to different HW (especially pump) and came across the update function of the PredictiveWeight class. If possible I would like to understand the idea behind the preassureDrop and puckRestistance calculations, but more importently I am wondering if the code in line 55 is meant to be like that:
pressureDrop -= pressureDrop - state.pumpClicks;
In my opinion this line can be rewritten to
pressureDrop = state.pumpClicks;

Is this intended or is the -= a mistake here?

Many thanks for all the work done and nice regards,
works24