A performer entertains the crowd during a rally in support of the leader of the Cameroonian opposition party Movement for the Rebirth of Cameroon (MRC) in Yaounde, on September 30, 2018, prior to the upcoming October 7, presidential elections. (Photo by Marco Longari/AFP Photo)

A Ballet dancer prepares backstage during the final dress rehearsal for the famous Nutcracker ballet by Pyotr Tchaikovsky at the Joburg Ballet, Johannesburg, South Africa, 04 October 2018. The premiere of Nutcracker is scheduled for 05 October and the show will run for two weeks. (Photo by Kim Ludbrook/EPA/EFE)

A Russian army conscript called up for service in the Kremlin regiment and a woman say farewell at Yekaterinburg-Passazhirsky railway station in Yekaterinburg, Russia on November 15, 2018. (Photo by Donat Sorokin/TASS Russian News Agency)

A young Sikh boy shouts religious slogans during a procession ahead of the birth anniversary of Guru Nanak in Jammu, India, Wednesday, November 21, 2018. The birth anniversary of Guru Nanak, founder of Sikhism and first Sikh guru, will be marked on Nov. 23. (Photo by Channi Anand/AP Photo)

University students demonstrate against the crisis in the public education, budget cuts and a tax reform project announced by the government of Ivan Duque in Medellin, Colombia on December 13, 2018. (Photo by Joaquín Sarmiento/AFP Photo)

A performer dances at a housing exhibition in Wuhan, Hubei province, China, September 27, 2015. (Photo by Reuters/Stringer)

An indigenous girl carries a monkey inside her house in their village at Xingu national park in Mato Grosso, Brazil, October 2, 2015. The Kamayura tribe consists of around 300 people, and is one of the 16 ethnic groups living in the indigenous Xingu national park. (Photo by Paulo Whitaker/Reuters)

David Nicholson, 21, surfs as "The Mask" during the ZJ Boarding House Haunted Heats Halloween Surf Contest in Santa Monica, California, United States, October 31, 2015. (Photo by Lucy Nicholson/Reuters)