Task: Question Answering
Input (English): The primary focus of Shoah is the stories of Holocaust survivors, perpetrators and witnesses. Instead of encompassing a traditional narrative document of these people, director Claude Lanzmann conducts in-depth interviews with his subjects, some of them, like SS Junior Sergeant (Unterscharfuhrer) Franz Suchomel and Franz Schalling, being filmed in secret. In all, the documentary encompasses over nine hours.Survivors that Lanzmann interviews include Simon Srebnik, a survivor of the Chelmno extermination camp, Abraham Bomba, a barber who cut the hair of women before they entered the gas chambers at Treblinka, and Rudolph Vrba, who escaped from Auschwitz and for producing the most detailed information about the exterminations taking place at the camp.Perpetrators interviewed included the aforementioned Suchomel, who describes the processions of prisoners to the gas chambers at Treblinka. He also talks at length about the construction of additional gas chambers. Henryk Gawkowski talks about driving the trains that brought prisoners to Treblinka while consuming vodka supplied to him by the Nazis.Witnesses to the Holocaust include Jan Karski, who was charged by Jewish leaders in the Warsaw ghetto with informing the Allies of the mass exterminations and with trying to procure weapons for the uprising. Other witnesses include the then-living residents of Treblinka who talk about the Jewish residents being removed to the ghettos. In a famous scene, they discuss the events with Lanzmann while Simon Srebnik stands with them.Lanzmann also talks at great length with Holocaust historian Raul Hilberg who talks about the logistics used by the Nazis to transport the millions of victims to the camps via the rail system, the Reichsbann. Hilberg also discusses the economics of the relocation and extermination of the victims., Question: What were some of director Claude Lanzmann's interviews of his subjects filmed in?
Output (English): Answer: secret.