A rescue worker holds an injured boy after what activists said were airstrikes carried out by the Russian air force in Idlib city, Syria December 20, 2015. (Photo by Ammar Abdullah/Reuters)

Andrey Karr from Western Riders Slacklines at sunset above big waves in Nazare, Portugal on December 27, 2017. (Photo by Aidan Williams/National Geographic Travel Photographer of the Year Contest)

An indigenous woman participates in a parade called "International Indigenous Beauty" during the first World Games for Indigenous Peoples in Palmas, Brazil, October 24, 2015. Billed as the indigenous Olympics, the games are expected to attract nearly 2,000 athletes from dozens of Brazilian ethnicities, as well as from such far-flung nations as Ethiopia and New Zealand. (Photo by Ueslei Marcelino/Reuters)

People look through the front windshield of a damaged trolleybus in Donetsk, January 22, 2015. At least seven civilians were killed on Thursday when a shell or a mortar hit a trolleybus stop in the rebel-controlled city of Donetsk in eastern Ukraine, a Reuters witness said. The Reuters cameraman said he saw six bodies on the ground near, and inside, a trolleybus in a southern district of the city. Windows of shops nearby had been blown out by the blast. (Photo by Alexander Ermochenko/Reuters)

Krysten Ritter is seen at Sundance Festival on January 19, 2014 in Park City, Utah. (Photo by Alo Ceballos/GC Images)

A young boy rests by empty USAID vegetable oil tins in the Dagahaley refugee camp which makes up part of the giant Dadaab refugee settlement on July 19, 2011 in Dadaab, Kenya. The refugee camp at Dadaab, located close to the Kenyan border with Somalia, was originally designed in the early 1990s to accommodate 90,000 people but the UN estimates over 4 times as many reside there. The ongoing civil war in Somalia and the worst drought to affect the Horn of Africa in six decades has resulted in an estimated 12 million people whose lives are threatened. (Photo by Oli Scarff/Getty Images)

Dancers from Xinjiang delegation perform during the Opening Ceremony for the 9th National Traditional Games of Ethnic Minorities of the People's Republic of China on September 10, 2011 in Guiyang, China. (Photo by Feng Li/Getty Images)