Yeah, it is a bit confusing. Try using the cheatsheet. But essentially, the reverse, reverses the locked state of the cell, so if cell is locked, it gets unlocked, if cell is unlocked, it gets locked. Vice versa if cell is locked it gets unlocked. When reverse points to each-other, they evaluate that multiple times. Assuming an unlocked cell: First reverse locks it, second reverse does the opposite, and unlocks it.