Opening hook The silence in the lecture hall was heavy, the kind that only exists right before a professor begins a final exam. I was three rows from the front, pen poised, when my phone vibrated against the wooden desk. The sound was like a jackhammer in the quiet.
Source: [Dev.to](https://dev.to/haseebthedev0/optimizing-geofencing-lessons-from-battery-management-in-android-lo8)