Smoko on the building site, and somebody has thrown every toolbox and snack tin into the air. Apples, bananas, oranges, sandwiches and the odd snack bar come flying, and your finger is the ruler. Drag a stroke through a whole fan of flying gear for stacking multipliers, chase the sprinkle bread, and steer around the wasps: three stings and you are off to first aid. A parked ruler cuts nothing. The stroke is the weapon.