See that shiny flagship phone dangling from the stranger's back pocket? You should think twice about trying to grab it, not only because it's a terrible thing to do, but also because it probably won't do you any good. By the time you've hot-footed it to the pawn shop to hawk your ill-gotten wares, it's increasingly likely that the phone will have been deactivated by a smartphone kill switch. The campaign, launched by San Francisco's George Gascón and Eric Schneiderman way back in 2013 appears to have been a success, helping to remove the perils of tweeting on dark city streets