A man from the Dani tribe cuts the head of a pig after cooked by traditional way which is use burned hot stones at Obia Village on August 9, 2014 in Wamena, Papua, Indonesia. The stone-age Dani tribe live a traditional existence in the Baliem Valley, which is situated 1600 metres above sea level in the heart of the Cyclops Mountains. (Photo by Agung Parameswara/Getty Images)

Igor Perne (L), 53, an electronic engineer and a member of the International Virtual Aviation Organisation (IVAO), and fellow virtual pilot Franc Lavric gesture for the camera before taking off on a virtual flight in a flight simulator in Nova Vas, Slovenia November 13, 2014. In 2011, Perne, a lifelong flying enthusiast, bought parts of a written-off Cyprus Airways airliner and then spent two and a half years turning the entire nose of the scrapped aircraft into an elaborate flight simulator. (Photo by Srdjan Zivulovic/Reuters)

Children exercise before a wrestling practice session at an old Basque ball game gymnasium in downtown Havana, October 30, 2014. (Photo by Alexandre Meneghini/Reuters)

A woman crosses a road outside the EU Parliament ahead of the EU elections in Brussels, Belgium, May 22, 2019. (Photo by Yves Herman/Reuters)

School leavers celebrate their graduation in Moscow's Red Square in Moscow, Russia on June 20, 2019. (Photo by Artyom Geodakyan/TASS)

English fashion model Daisy Lowe attends day ten of the Wimbledon Tennis Championships at All England Lawn Tennis and Croquet Club on July 11, 2019 in London, England. (Photo by Paul Edwards/The Sun)

Japan's delegation gather to sign the formal surrender document on the U.S. Navy battleship USS Missouri in Tokyo Bay in a September 2, 1945 file photo. (Photo by Reuters/US Navy)

A boy carries sugar cane through a farm on the outskirt of Zaria in Nigeria's northern state of Kaduna November 15, 2016. (Photo by Akintunde Akinleye/Reuters)