Ha ha ha. Plymouth’s superintendent of schools, Gary Maestas, allowed himself a short laugh. He was thinking about the real-time vape detectors he’s planning to install in the town’s high school bathrooms, and how the students don’t yet know. “They’ll find out soon enough,” Maestas said. Ha ha ha. But the kids — they’re not the ones Maestas is laughing at. The children are the ones he’s trying to protect — from a multibillion-dollar vaping and e-cigarette industry that has lured millions of teenagers with sexy branding and child-friendly flavors, and along the way turned school bathrooms into ground zero of the vaping wars.