A Mai-Mai rebel soldier shows off his guns at a checkpoint near the Mugunga refugee camp in Zaire; 1996. (Photo by Carol Guzy/The Washington Post)

In this June 23, 2015 photo, Ashaninka Indian beauty contestants pose for a photo with members of a visiting music group, hired to perform during the annual founding anniversary festivities, in Otari Nativo, Pichari, Peru. The contestants wear the simple brown dresses of the Ashaninka woman, their faces dotted in a traditional design with a red dye extracted from a spice called achiote. (Photo by Rodrigo Abd/AP Photo)

Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

Waves hit the seawall during heavy seas and high winds in Dawlish in south west Britain, February 2, 2017. (Photo by Toby Melville/Reuters)

People play with foam at a water park in Yantai, Shandong province, China June 16, 2107. (Photo by Reuters/Stringer)

A man dressed up as the devil jumps over babies lying on a mattress in the street during “El Colacho”, the “baby jumping festival” in the village of Castrillo de Murcia, near Burgos on June 18, 2017. Baby jumping (El Colacho) is a traditional Spanish practice dating back to 1620 that takes place annually to celebrate the Catholic feast of Corpus Christi. During the act – known as El Salto del Colacho (the devil's jump) or simply El Colacho – men dressed as the Devil jump over babies born in the last twelve months of the year who lie on mattresses in the street. (Photo by Cesar Manso/AFP Photo)

A pilot inflates a hot air balloon while taking part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. The festival takes place from 23 to 31 January. (Photo by Vincent Vannay/EPA)

A robot named “Robovie-II”, developed by Japanese robotics research institution ATR, moves around at a grocery store during a shopping assisting experiment by utilizing the robot in an ubiquitous network technology platform in Kyoto, western Japan January 6, 2010. (Photo by Yuriko Nakao/Reuters)