Passage: The original play was inspired by a trip to Europe made by Murray Burnett and his wife in 1938, during which they visited Vienna shortly after the Anschluss and were affected by the anti-Semitism they saw. In the south of France, they went to a nightclub that had a multinational clientele, among them many exiles and refugees, and the prototype of Sam. In The Guardian, Paul Fairclough writes that Cinema Vox in Tangier "was Africa's biggest when it opened in 1935, with 2,000 seats and a retractable roof. As Tangier was in Spanish territory [sic], the theatre's wartime bar heaved with spies, refugees and underworld hoods, securing its place in cinematic history as the inspiration for Rick's Cafe in Casablanca." The scene of the singing of La Marseillaise in the bar is attributed by the film scholar Julian Jackson as an adaptation of a similar scene from Jean Renoir's film from 5 years before titled La Grande Illusion.The first writers assigned to the script were twins Julius and Philip Epstein who, against the wishes of Warner Brothers, left at Frank Capra's request early in 1942 to work on the Why We Fight series in Washington, D.C. While they were gone, the other credited writer, Howard Koch, was assigned; he produced thirty to forty pages. When the Epstein brothers returned after about a month, they were reassigned to Casablanca and—contrary to what Koch claimed in two published books—his work was not used. The Epstein brothers and Koch never worked in the same room at the same time during the writing of the script. In the final budget for the film, the Epsteins were paid $30,416, and Koch earned $4,200.In the play, the Ilsa character is an American named Lois Meredith; she does not meet Laszlo until after her relationship with Rick in Paris has ended. Rick is a lawyer. The play (set entirely in the cafe) ends with Rick sending Lois and Laszlo to the airport.  To make Rick's motivation more believable, Wallis, Curtiz, and the screenwriters decided to set the film before the attack on Pearl Harbor.The...

Question: When did Mr and Mrs Burnett take a trip?
1938