Book excerpt: This is a Holocaust story like very few others. It's about a youngster who turned on his persecutors and showed them that Jewish blood is not cheap. And he lived to tell his story! A. Romi Cohn -- today a well-known mohel, businessman and philanthropist -- was a precocious, active 10-year-old yeshivah student when the Nazis invaded Poland. Soon afterward, they and their puppet regime took over his native Czechoslovakia. The Nazis did not have to round up Czech Jews, the Czechs did it for them, and even paid the conqueror to take the Jews off their hands.