WHEN WORLD leaders meet Donald Trump, flattery has its uses but it is “not a silver bullet”. That is the considered view of foreign diplomats and American officials who have, between them, spent hundreds of hours in the room with America’s 45th and soon to be 47th president. Their counsel is a timely corrective. For the usual wisdom on how to handle Mr Trump could double up as advice on hosting a toddler’s birthday party, with its emphasis on lavish presents, easy-to-eat food and unlimited praise.