Former Twitter CEO Parag Agrawal (@paraga) on what fighting bots & influence campaigns at Twitter taught him: “The thing most people don't understand is, it is almost impossible to take it to zero. You have to contain it because it is a knife fight & the tactics change.” “Most of the bad stuff is stuff that doesn't show up on the surface. If you saw an account & thought, ‘This is a bot,’ it's harmless because you could see that it's a bot. The real problem is going to be in the margins when…