Close came back into my head as I was reading Sam Wasson’s new book “Improv Nation” (Houghton Mifflin Harcourt), a very readable and admiring — triumphalist, you might say — exploration of how the Compass Players and Second City changed the world of American comedy and invented a new American art form that today is to scripted performance what jazz is the concerto. It’s a Chicago-centric narrative (“In the 1990s,” Wasson writes, accurately enough, “Chicago was the Florence of the improv renaissance”) that is very familiar to many of us in this city, especially to those of us in the seats for its creation. But before Wasson’s book, it rarely has been amply credited or understood out of town, since the Tina Feys and Joan Riverses and Stephen Colberts all had to go out of town for their careers to progress. Plus ca change.