Gary Shteyngart is a best-selling novelist and globetrotter. He came to this country with his family from Leningrad in 1979, and his work has become a touchstone of literature about the Russian Jewish immigrant experience. His third novel is now out, “Super Sad True Love Story” (Random House) and in it, the sweet if schlubby Lenny Abramov clings desperately to books in a culture that can’t read, while falling in love with one of illiteracy’s young victims. Both are children of immigrants, and the couple tries to stay together amidst an America that is crumbling around them. When Shteyngart visited the Forward studios we talked about Jews who fetishize the shtetl, adult circumcision and love in the age of screens.