Waura Indians wrestle during this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, Brazil August 25, 2013. (Photo by Ueslei Marcelino/Reuters)

Tracy Sarita celebrates the sunrise during the Burning Man 2015 “Carnival of Mirrors” arts and music festival in the Black Rock Desert of Nevada, September 3, 2015. Approximately 70,000 people from all over the world are gathering at the sold-out festival to spend a week in the remote desert to experience art, music and the unique community that develops. (Photo by Jim Urquhart/Reuters)

Mud Madness at the annual Jaffa Cakes charity three-mile run at Foymore Lodge near Portadown this afternoon, on April 13, 2014. A total of a thousand competitors and fun-runners took part in the two races held over the mudstrewn endurance course. (Photo by Alan Lewis/Photopress Belfast)

Andrea Petkovic of Germany in action against Sara Errani of Italy during day one of the Mutua Madrid Open tennis tournament at the Caja Magica on May 3, 2014 in Madrid, Spain. (Photo by Julian Finney/Getty Images)

U.S. Corporal Stanley Suski, left, and Miss Tamako, a Geisha girl, whirl a bit of Jitterbug, in a bar, in Tokyo, Japan, on October 1, 1945. (Photo by AP Photo)

A monument to the character of Darth Vader from "Star Wars", which was rebuilt from a statue of Soviet state founder Vladimir Lenin, is seen in Odessa, Ukraine, October 23, 2015. The Internet Party of Ukraine's main candidate, a person named for the legendary "Star Wars" villain Darth Vader, campaigned in Odessa, cruising through town on a black van to the sound of Imperial March from "Star Wars" saga. (Photo by Yevgeny Volokin/Reuters)

Philippine President Rodrigo Duterte looks at Miss Universe candidates at the presidential palace in Manila, Philippines January 23, 2017. (Photo by Erik De Castro/Reuters)

Refugees and migrants try to find a place on an already full train headed for Serbia, near the city of Gevgelija, The Former Yugoslav Republic of Macedonia, on February 24, 2016. Refugees and migrants from Iraq and Syria continue to pass through Macedonia on their way to the European Union. (Photo by Georgi Licovski/EPA)