An armed man herds his cattle close to the village of Nimini in northern South Sudan, February 8, 2017. In the chaos of South Sudan's civil war, it took three years for Nyagonga Machul to find her lost children. Machul had traveled from her village to the capital when President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer, in 2013. (Photo by Siegfried Modola/Reuters)

Assi Mbengue nibbles as she prepares for the start of Las Palmas' Carnival Queen ceremony in Las Palmas, Spanish Canary Island of Gran Canaria, February 24, 2017. (Photo by Borja Suarez/Reuters)

Dancers perform at a Carnival parade in Les Cayes, Haiti, Tuesday, February 28, 2017. Haiti's three-day Carnival festivities have brought rum-fueled parties, imaginative costumes and high-energy dance music to a southern city that's still recovering from last year's punishing Hurricane Matthew. (Photo by Dieu Nalio Chery/AP Photo)

A youth in make-up waits for the start of the annual Zombie walk in Mexico City, Saturday, October 22, 2016. Hundreds dressed in rags and ghoulish makeup to look bloody and decaying, gathered in the historic center of Mexico's capital. (Photo by Christian Palma/AP Photo)

A woman prays at the edge of a river during a protest against the building of a pipeline near the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S. November 2, 2016. (Photo by Stephanie Keith/Reuters)

Monaco's Princess Charlotte Casiraghi arrives to attend a mass at the Saint Nicholas Cathedral during the celebrations marking Monaco's National Day, on November 19, 2016 in Monaco. (Photo by Valery Hache/Reuters)

Members of a cheerleading team warm- up during the Russian Cheerleading Championship of students in Moscow on November 20, 2016. (Photo by Natalia Kolesnikova/AFP Photo)

A narrow strip of clouds illuminated in the light of sunset before approaching rain clouds over an alley near Sieversdorf district Oder-Spree, Brandenburg, Germany on July 14, 2016. (Photo by Patrick Pleul/DPA)